[ { "id": "authors:7f7pj-2wk79", "collection": "authors", "collection_id": "7f7pj-2wk79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-142845367", "type": "article", "title": "The extension of the Hubble diagram. II - New redshifts and photometry of very distant galaxy clusters - First indication of a deviation of the Hubble diagram from a straight line", "author": [ { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Redshifts are given for 50 brightest cluster galaxies, extending as far as z = 0.75; BVR photometry is given for 33 clusters. These data are combined with earlier data of a similar kind in order to investigate several effects. The measured B - V and V - R colors as a function of redshift are well represented by Whitford's standard-galaxy K corrections, as far as these are defined (to z = 0.28 in B - V and z = 0.48 in V - R). This suggests both that the K corrections are valid over these ranges of z and that no major color change of the galaxies has occurred over the last 4-5 x 10^9 years. At larger redshifts, the colors, which start out being monotonically redder with z, turn over and become bluer with z. The data at large z seem to follow the prediction based upon ultraviolet photometry of NGC 4486 (M87), which is one extreme of a range of galaxies\nmeasured by Code and Welch.\nOther standard corrections to the measurements are discussed, and formal least-squares values of q_0 are computed. To explore the possibility that one might be stalemated by the fact that the value of q_0 must, in principle, be known a priori to compute the aperture correction, the data are corrected separately for assumed q_0 values of 0 and + 1. The subsequently computed values of\nq_0 differ by only 0.2 between the two cases, which indicates that a simple iterative procedure will converge to produce a self-consistent value of q_0. The new data do not significantly change earlier discussions of the corrections for cluster richness and Bautz-Morgan contrast type. If these two corrections are not made, the effect on the present data is to significantly increase the positive\ncurvature of the Hubble diagram, as well as the dispersion in apparent magnitude. To within the limits of the present data, the absolute magnitude of the brightest cluster galaxy does not, in general, depend on whether it is also a bright radio source. \nThe present sample, cut off at z = 0.4 to avoid selection effects and uncertainties in the data, shows the first significant evidence for curvature of the Hubble diagram, with V and R magnitudes giving similar results. The formal value of q_0 (with galaxy evolution ignored) is + 1.6 \u00b1 0.4.\nThe dispersion in absolute magnitude is less than 0.3 mag, with M_v = -23.28 \u00b1 0.03 and M_R= -24.09 \u00b1 0.03.\nThe use of the Hubble diagram in cosmology now depends on a knowledge of brightness changes in galaxies, on the one hand, or of q_0 from other evidence, on the other. For example, if it were known with certainty that there has been no significant change in elliptical galaxy luminosities\nduring the last 4 x 10^9 years, then the present data are nearly good enough for one to say definitively that the universe is closed and finite, with a finite lifetime. At the other extreme, if it were known with certainty from other evidence that the universe was nearly empty (q_0 \u2248 0), then the present data set the constraint that net galaxy luminosities have decreased by ~ 0.5 mag during\nthe last 5 x 10^9 years, with a net color change \u0394(B - V) \u2264 0.1 mag. It seems possible at present to construct a self-consistent model with q_0 \u2248 0 that satisfies the known data, but the case is not yet settled.", "doi": "10.1086/156038", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2015-09-08", "series_number": "1", "volume": "221", "issue": "1", "pages": "383-394" }, { "id": "authors:6a8k2-axp82", "collection": "authors", "collection_id": "6a8k2-axp82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GARbams04", "type": "article", "title": "Overlooked examples of cloud self-organization at the mesoscale", "author": [ { "family_name": "Garay", "given_name": "Michael J.", "orcid": "0000-0002-1374-5074", "clpid": "Garay-M-J" }, { "family_name": "Davies", "given_name": "Roger", "clpid": "Davies-R" }, { "family_name": "Averill", "given_name": "Clare", "clpid": "Averill-C" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Stratocumulus clouds are common in the tropical and subtropical marine boundary layer, and understanding these clouds is important due to their significant impact on the earth's radiation budget. Observations show that the marine boundary layer contains complex, but poorly understood processes, which, from time to time, result in the observable self-organization of cloud structures at scales ranging from a few to a few thousand kilometers. Such shallow convective cloud features, typically observed as hexagonal cells, are known generally as mesoscale cellular convection (MCC). Actinoform clouds are rarer, but visually more striking forms of MCC, which possess a radial structure. \n\nBecause mesoscale cloud features are typically too large to be observed from the ground, observations of hexagonal cells historically date only to the beginning of satellite meteorology. Examples of actinoform clouds were shown in the venerable \"Picture of the Month\" series in Monthly Weather Review in the early 1960s, but these clouds were generally forgotten as research focused on hexagonal cells. \n\nRecent high-resolution satellite images have, in a sense, \"rediscovered\" actinoform clouds, and they appear to be much more prevalent than had been previously suspected. We show a number of examples of actinoform clouds from a variety of locations worldwide. In addition, we have conducted a detailed case study of an actinoform cloud system using data from the Multiangle Imaging SpectroRadiometer (MISR) and the Geostationary Operational Environmental Satellite (GOES), including analysis of cloud heights, radiative properties, and the time-evolution of the cloud system. We also examine earlier theories regarding actinoform clouds in light of the new satellite data.", "doi": "10.1175/BAMS-85-10-1585", "issn": "0003-0007", "publisher": "Bulletin of the American Meteorological Society", "publication": "Bulletin of the American Meteorological Society", "publication_date": "2004-10-01", "series_number": "10", "volume": "85", "issue": "10", "pages": "1585-1594" }, { "id": "authors:52ggd-w7e78", "collection": "authors", "collection_id": "52ggd-w7e78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181213-143632330", "type": "book_section", "title": "Design considerations for a novel phase-contrast adaptive-optic wavefront sensor", "book_title": "Adaptive Optics Systems and Technology II", "author": [ { "family_name": "Bloemhof", "given_name": "E. E.", "clpid": "Bloemhof-E-E" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "contributor": [ { "family_name": "Tyson", "given_name": "Robert K.", "clpid": "Tyson-R-K" }, { "family_name": "Bonaccini", "given_name": "Domenico", "clpid": "Bonaccini-D" }, { "family_name": "Roggeman", "given_name": "Michael C.", "clpid": "Roggeman-M-C" } ], "abstract": "The wavefront sensor (WFS) is perhaps the most critical adaptive-optic subsystem, particularly for astronomical applications with natural guide stars, where current WFS sensitivity limitations seriously restrict sky coverage. In this paper, we discuss the possibility of a WFS based on a phase-contrast principle of the sort employed by Zernike for microscopy. Such a WFS would be implemented by inserting a focal-plane filter with a (pi) /2 phase-shifting central spot having a transverse size of the order of the diffraction limit. The result would be an image of the pupil in which intensity is directly proportional to the seeing- and aberration-induced phase variations over the pupil. In comparison, the signals produced by the two most common current WFS schemes, Shack-Hartmann and curvature sensing, are proportional to the phase slope and to the second derivative, respectively. The phase-contrast approach might derive some advantages stemming from its more natural match to the control eigenvectors of the electrostrictive deformable mirrors that are expected to predominate in high-order adaptive optics systems, in the same way that curvature sensors are currently well matched to bimorph mirrors. It may thus yield substantial performance improvements with simpler hardware and lighter computational loads. We examine this and other possible advantages of the phase-contrast WFS, and investigate some of the practical design issues involved in its implementation.", "doi": "10.1117/12.454812", "isbn": "9780819442086", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "2002-02-04", "pages": "363-370" }, { "id": "authors:w4bk9-see56", "collection": "authors", "collection_id": "w4bk9-see56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141111-113040508", "type": "article", "title": "Mapping Jupiter's Latitudinal Bands and Great Red Spot Using HST/WFPC2 Far-Ultraviolet Imaging", "author": [ { "family_name": "Vincent", "given_name": "Mark B.", "clpid": "Vincent-M-B" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Harris", "given_name": "Walter M.", "clpid": "Harris-W-M" }, { "family_name": "West", "given_name": "Robert A.", "orcid": "0000-0002-4320-2599", "clpid": "West-R-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Jupiter's low and mid-latitudes are examined using ultraviolet (UV) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994\u20131997. Effective atmospheric pressures probed by the F160W, F218W, and F255W are estimated at 100, 165, and 370 mbar, respectively, at low latitudes. Far-ultraviolet images of Jupiter taken with the F160W filter reveal bright and dark latitudinal bands at low and mid-latitudes. These bands were found to be correlated with the zonal winds; the bright bands are at latitudes of subsidences, and the dark bands at upwellings. The sense of this correlation is opposite to that seen in visible images of Jupiter where the bright zones are located over upwellings, and dark belts over subsidences. The locations of the dark bands seen in the F160W images are consistent with enhanced concentrations of NH_3 and/or aerosols in the upwellings near the tropopause. Anticyclonic ovals, like the Great Red Spot, are regions of upwellings, and also appear dark in the F160W images. Temporal variations were also observed in the contrast of the low-latitude bands. An increase in the contrast of the low-latitude bands appeared to coincide with a visible wavelength broadening of the North Equatorial Belt that occurred in early to mid-1996. Changes at mid-southern latitudes were observed in the aftermath of the SL-9 impacts in July 1994.", "doi": "10.1006/icar.1999.6232", "issn": "0019-1035", "publisher": "Elsevier", "publication": "Icarus", "publication_date": "2000-02", "series_number": "2", "volume": "143", "issue": "2", "pages": "189-204" }, { "id": "authors:7x1zn-tsp92", "collection": "authors", "collection_id": "7x1zn-tsp92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141111-131715271", "type": "article", "title": "Jupiter's Polar Regions in the Ultraviolet as Imaged by HST/WFPC2: Auroral-Aligned Features and Zonal Motions", "author": [ { "family_name": "Vincent", "given_name": "Mark B.", "clpid": "Vincent-M-B" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Harris", "given_name": "Walter M.", "clpid": "Harris-W-M" }, { "family_name": "West", "given_name": "Robert A.", "orcid": "0000-0002-4320-2599", "clpid": "West-R-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Jupiter's polar regions are examined using ultraviolet (UV, 120\u2013320 nm) images obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 over the period of 1994\u20131997. These images probe the stratospheric aerosols at pressures of a few tens of millibars. We discovered a UV-darkened segment in the polar shading just equatorward of the north polar hood that remained aligned with the southern-most portion of the north auroral oval. The darkened segment generally extended over 100\u00b0\u2013260\u00b0 System III longitude, and 39\u00b0\u201353\u00b0N planetocentric latitude in the F160W, F218W, and F255W images. No single type of feature in the F218W and F255W images appeared consistently aligned within the outline of the north auroral oval, but several transient features were observed. It is not certain whether these transient features were associated with auroral processes, or just coincidentally aligned. A \"south dark patch\" was consistently observed within the outline of the south auroral oval and was temporally variable in size and shape. By tracking selected features, we obtained the first direct measurements of the zonal motions in Jupiter's high-latitude stratosphere. Primarily retrograde motions were observed from 41\u00b0N to 60\u00b0N. Both prograde and retrograde motions appeared from 48\u00b0S to 71\u00b0S. We propose that the asymmetric appearance of the polar hoods (R. A. West 1979, Icarus 38, 12\u201333; R. Wagener and J. Caldwell 1988, Icarus 74, 141\u2013152) is influenced, in part, by meridional mixing in the stratosphere. Enhanced meridional mixing would tend to be more effective at dispersing the polar aerosols to lower latitudes in the north than in the south.", "doi": "10.1006/icar.1999.6233", "issn": "0019-1035", "publisher": "Elsevier", "publication": "Icarus", "publication_date": "2000-02", "series_number": "2", "volume": "143", "issue": "2", "pages": "205-222" }, { "id": "authors:h8s2y-6rn08", "collection": "authors", "collection_id": "h8s2y-6rn08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-131227664", "type": "article", "title": "WFPC2 observations of compact star cluster nuclei in low-luminosity spiral galaxies", "author": [ { "family_name": "Matthews", "given_name": "Lynn D.", "clpid": "Matthews-L-D" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have used the Wide Field Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope to obtain F450W and F814W (B- and I-band) observations of the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242, and ESO 359-029. In addition, we analyze archival WFPC2 observations of the compact star cluster nucleus of M33. All of these galaxies are structurally diffuse, with moderately low surface brightnesses and little or no discernible bulge component. Here we present a comparative analysis of the structural and photometric properties of their nuclei. NGC 4395 contains a Seyfert 1 nucleus; M33 has some signatures of weak nuclear activity; the other two galaxies are not known to be active. All of the nuclei have M_I ~ -11; hence these represent a little explored low-luminosity extension of the galactic nuclear activity sequence in a class of host galaxy not traditionally associated with galactic nuclear phenomena. These kinds of compact nuclei appear to be quite common in low luminosity, late-type spirals. Our Planetary Camera 2 images partially resolve the nuclei of all four galaxies. A simple model consisting of an isothermal sphere plus a point source provides a good model for the observed radial intensity distribution in all cases and permits an exploration of the underlying nuclear structures and spatial scales. Despite their low luminosities, all of the nuclei are very compact. In all cases the luminosity densities are increasing at small radii to the resolution limit of our data. In spite of having similar size scales and luminosities, the nuclei in our sample span a wide range of B-I color. This may be a signature of different evolutionary phases. The M33 nucleus exhibits complex structure; its isophotes are elongated, and it has a possible jetlike component. The Seyfert nucleus of NGC 4395 has an extremely blue color (B-I = -0.16) and is the most structurally complex nucleus in our sample. Circularly symmetric fits to its underlying structure reveal a distinct bipolar pattern. A pair of bright filaments located on one side of the nucleus are probably due to O III] emission from gas within a nuclear ionization cone. NGC 4395 appears to contain an underlying normal star cluster nucleus that is hosting activity. NGC 4242 shows evidence of a slightly elongated, bar-shaped feature at its center. The ESO 359-029 nucleus appears relatively symmetric and featureless at the resolution limit of our data, but it is clearly very compact. The circumnuclear environments of all four of our program galaxies are extremely diffuse, have only low to moderate star formation, and appear to be devoid of large quantities of dust. The central gravitational potentials of the galaxies are also quite shallow making the origin of these types of \"naked\" nuclei problematic.", "doi": "10.1086/300909", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1999-07", "series_number": "1", "volume": "118", "issue": "1", "pages": "208-235" }, { "id": "authors:ryc3f-tte49", "collection": "authors", "collection_id": "ryc3f-tte49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-095415093", "type": "article", "title": "Detection of surface brightness fluctuations in NGC 4373 using the Hubble Space Telescope", "author": [ { "family_name": "Pahre", "given_name": "Michael A.", "clpid": "Pahre-M-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Dressler", "given_name": "Alan", "clpid": "Dressler-A" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Surface brightness fluctuations (SBF) have been detected for three elliptical galaxies-NGC 3379 in the Leo group, NGC 4406 in the Virgo cluster, and NGC 4373 in the Hydra-Centaurus supercluster-using marginally sampled, deep images taken with the Planetary Camera of the WFPC2 instrument on the Hubble Space Telescope (HST). The power spectrum of the fluctuations image is well fitted by an empirical model of the point-spread function constructed using point sources identified in the held. Comparison with high-quality ground-based observations of all three galaxies show excellent agreement in the measurement of the distance modulus over a substantial range in distance. This demonstrates the capability of the Planetary Camera of WFPC2 to measure distances using the SBF technique despite the marginal sampling and small spatial coverage of the images. The residual variance due to unresolved sources in all three galaxies is only 2%-5% of the detected fluctuations signal, which confirms the advantage of HST imaging in minimizing the uncertainty of this SBF correction. Extensive consistency checks, including an independent SBF analysis using an alternate software package, suggest that our internal uncertainties are <0.02 mag. The fluctuations magnitude for NGC 4373 is /_(F814W) = 31.31\u00b10.05 mag, corresponding to a distance modulus of (m-M)_0 = 32.99\u00b10.11. This implies a peculiar velocity for this galaxy of 415\u00b1330 km s^(-1), which is smaller than derived from the D_n-\u03c3 relation.", "doi": "10.1086/306998", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1999-04-10", "series_number": "1", "volume": "515", "issue": "1", "pages": "79-88" }, { "id": "authors:98rrd-dnr91", "collection": "authors", "collection_id": "98rrd-dnr91", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150123-132606400", "type": "article", "title": "Deep Hubble Space Telescope observations of blue star clusters in NGC 3597", "author": [ { "family_name": "Carlson", "given_name": "Matthew N.", "clpid": "Carlson-M-N" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have analyzed HST/WFPC2 images of NGC 3597 and find ~700 compact objects surrounding the galaxy with an average (B-R)_0~0.6. We propose that the majority of these objects are young globular clusters. They have a spread in colors that is consistent with that expected for a population of young clusters with a common age and spread induced by photometric errors and reddening within NGC 3597. If these objects were similar to the Galactic globular cluster system seen at a younger age, we would predict a turnover in the luminosity function at B~23. However, we find that the luminosity function for the clusters is increasing to the limits of our photometry (B~27).", "doi": "10.1086/300819", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1999-04", "series_number": "4", "volume": "117", "issue": "4", "pages": "1700-1707" }, { "id": "authors:v7zgk-kxs36", "collection": "authors", "collection_id": "v7zgk-kxs36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120119-070830756", "type": "article", "title": "Hubble Space Telescope Imaging of the Circumstellar Nebulosity of T Tauri", "author": [ { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Short-exposure Planetary Camera images of T Tauri have been obtained using broadband filters spanning the wavelength range 0.55-0.80 \u03bcm. The optically visible star lies very close to an arc of reflection nebulosity. The arc's northern arm extends approximately 5\" from the star, while its southwestern arm appears brighter and extends only 2\". The arc shows an approximate symmetry along an axis toward the west-northwest, the direction of Hind's Nebula and the blueshifted molecular outflow. The morphology of the reflected light is similar to models of scattered light within an illuminated, axisymmetric outflow cavity in a circumbinary envelope, viewed \u2248 45\u00b0 from the outflow axis. However, our model images do not successfully account for the amount of limb brightening that is seen. No optical counterpart to the infrared companion is seen to a limiting magnitude of V = 19.6, which suggests A_V > 7 mag toward this source. There is no evidence for an optical tertiary, to a limiting \u0394V = 5.1 mag fainter than the primary, at the position where such an object has been previously reported.", "doi": "10.1086/306422", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1998-12-01", "series_number": "2", "volume": "508", "issue": "2", "pages": "736-743" }, { "id": "authors:6e1yz-79c53", "collection": "authors", "collection_id": "6e1yz-79c53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-095628407", "type": "article", "title": "WFPC2 studies of the Crab Nebula. II. Ionization structure of the Crab filaments", "author": [ { "family_name": "Sankrit", "given_name": "Ravi", "clpid": "Sankrit-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Scowen", "given_name": "P. A.", "clpid": "Scowen-P-A" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "R. W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John", "clpid": "Krist-J-E" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Narrowband images of the Crab Nebula taken with the Hubble Space Telescope (HST) WFPC2 show the morphology and ionization structure of the filaments in great detail. At HST resolution, low- and high-ionization emission from filaments in the Crab differ in two complementary respects. First, low-ionization emission is found to be concentrated in very sharp structures, while high-ionization emission is predominantly found in a much more diffuse component. For example, approximately 80% of emission from [O I]\u03bb6300 arises in features with scales of less than 0\".5, while only 10% of [O III]\u03bb5007 emission arises in such compact structures. Second, individual filaments are found to lie along a sequence of ionization structures, ranging from features in which all lines are concentrated in the same compact volume through features with low-ionization cores surrounded by high-ionization envelopes. Hester and coworkers proposed in 1996 that this sequence can be understood as the result of the nonlinear development of magnetic Rayleigh-Taylor (R-T) instabilities along the interface between the Crab synchrotron nebula and swept-up ejecta. We present photoionization models of cylindrically symmetrical filaments consisting of a quadratic core surrounded by an extended envelope. A good deal of the observed variation in filament structure in the Crab can be matched by varying the assumed density profiles in these models. This implies that variations in the development of R-T instabilities in the Crab account for much of the spectral variation within the remnant. We also present a photoionization model of a uniform, low-density medium, which reasonably matches the extended diffuse component that dominates the high-ionization emission. This envelope model produces strong [O III] but virtually no [O I]. While the He I/H\u03b2 ratio remains fairly constant throughout a range of filament models, this ratio is a factor of 5 lower in the envelope model. We find that the apertures used in ground-based spectroscopy of the Crab generally include emission from several discrete filaments as well as a component of diffuse emission. This places a fundamental limit on what can be inferred reliably from comparison of spectra with one-dimensional photoionization models. Many filament cores coincide with dust extinction features seen in a continuum image of the Crab. We consider one such feature in detail and find that the extinction of about 1.2 mag suggests that the dust-to-gas mass ratio may be an order of magnitude higher than is typical in the interstellar medium.", "doi": "10.1086/306078", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1998-09-01", "series_number": "1", "volume": "504", "issue": "1", "pages": "344-358" }, { "id": "authors:p90q6-kn278", "collection": "authors", "collection_id": "p90q6-kn278", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-091533170", "type": "article", "title": "Hubble Space Telescope WFPC2 Imaging of FS Tauri and Haro 6-5B", "author": [ { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have observed the field of FS Tauri (Haro 6-5) with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Centered on Haro 6-5B and adjacent to the nebulous binary system of FS Tauri A there is an extended complex of reflection nebulosity that includes a diffuse, hourglass-shaped structure. H6-5B, the source of a bipolar jet, is not directly visible but appears to illuminate a compact, bipolar nebula which we assume to be a protostellar disk similar to HH 30. The bipolar jet appears twisted, which explains the unusually broad width measured in ground-based images. We present the first resolved photometry of the FS Tau A components at visual wavelengths. The fluxes of the fainter, eastern component are well matched by a 3360 K blackbody with an extinction of A_V = 8. For the western star, however, any reasonable, reddened blackbody energy distribution underestimates the K-band photometry by over 2 mag. This may indicate errors in the infrared photometry or errors in our visible measurements due to bright reflection nebulosity very close to the star. The binary was separated by 0.\"239 \u00b1 0.\"005 at a position angle of 84\u00b0 \u00b1 1.\"5 on 1996 January 25. There is no nebulosity around FS Tau A at the orientation suggested for a disk based on previous, ground-based polarization measurements.", "doi": "10.1086/305861", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1998-07-10", "series_number": "2", "volume": "501", "issue": "2", "pages": "841 -852" }, { "id": "authors:6tc6y-c1k22", "collection": "authors", "collection_id": "6tc6y-c1k22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150122-094435044", "type": "article", "title": "Ionization structure in the 30 Doradus Nebula as seen with Hubble Space Telescope Wide Field Planetary Camera 2", "author": [ { "family_name": "Scowen", "given_name": "P. A.", "clpid": "Scowen-P-A" }, { "family_name": "Hester", "given_name": "J. J.", "clpid": "Hester-J-J" }, { "family_name": "Sankrit", "given_name": "R.", "clpid": "Sankrit-R" }, { "family_name": "Gallagher", "given_name": "J. S.", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "G. E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "C. J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "J. T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "D.", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "R. W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "R. E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "J. G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "J. A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "J.", "clpid": "Krist-J" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Stapelfeldt", "given_name": "K. R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "J. T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "A. M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Using the Hubble Space Telescope (HST) and Wide Field Planetary Camera 2, we have imaged the central 20 pc of the giant H II region 30 Doradus Nebula in three different emission lines. The images allow us to study the nebula with a physical resolution that is within a factor of 2 of that of typical ground-based observations of Galactic H II regions. We present a gallery of interesting objects within the region studied. These include a tube blown by the wind of a high-velocity star and a discrete H II region around an isolated B star. This small isolated H II region appears to be in the midst of the champagne flow phase of its evolution. Most of the emission within 30 Dor is confined to a thin zone located between the hot interior of the nebula and surrounding dense molecular material. This zone appears to be directly analogous to the photoionized photoevaporative flows that dominate emission from small, nearby H II regions. For example, a column of material protruding from the cavity wall to the south of the main cluster is found to be a direct analog to elephant trunks in M16. Surface brightness profiles across this structure are very similar to surface brightness profiles taken at ground-based resolution across the head of the largest column in M16. The dynamical effects of the photoevaporative flow can be seen as well. An arcuate feature located above this column and a similar feature surrounding a second nearby column are interpreted as shocks in which the photoevaporative flow stagnates against the high-temperature gas that fills the majority of the nebula. The ram pressure in the photoevaporative flow, derived from thermal pressure at the surface of the column, is found to balance with the pressure in the interior of the nebula derived from previous X-ray observations. By analogy with the comparison of ground-based and HST images of M16, we infer that the same sharply stratified structure seen in HST images of M16 almost certainly underlies the observed structure in 30 Doradus, which is a crucial case because it allows us to bridge the gap between nearby H II regions and the giant H II regions seen in distant galaxies. The real significance of this result is that it demonstrates that the physical understanding gained from detailed study of photoevaporative interfaces in nearby H II regions can be applied directly to interpretation of giant H II regions. Stated another way, interpretation of observations of giant H II regions must account for the fact that this emission arises not from expansive volumes of ionized gas but instead from highly localized and extremely sharply stratified physical structures.", "doi": "10.1086/300411", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1998-07", "series_number": "1", "volume": "116", "issue": "1", "pages": "163-179" }, { "id": "authors:stnp7-jya03", "collection": "authors", "collection_id": "stnp7-jya03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120119-090051590", "type": "monograph", "title": "HST Imaging of the Circumstellar Nebulosity of T Tauri", "author": [ { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Short exposure Planetary Camera images of T Tauri have been obtained using broadband filters spanning the wavelength range 0.55-0.80 mu. The optically visible star lies very close to an arc of reflection nebulosity.", "publisher": "Jet Propulsion Laboratory", "publication_date": "1998-06" }, { "id": "authors:hvzks-p6s09", "collection": "authors", "collection_id": "hvzks-p6s09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150122-093027737", "type": "article", "title": "Deep Hubble Space Telescope observations of star clusters in NGC 1275", "author": [ { "family_name": "Carlson", "given_name": "Matthew N.", "clpid": "Carlson-M-N" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present an analysis of compact star clusters in deep Hubble Space Telescope Wide Field Planetary Camera 2 images of NGC 1275. B- and R-band photometry of roughly 3000 clusters shows a bimodality in the B-R colors, suggesting that distinct old and young cluster populations are present. The small spread in the colors of the blue clusters is consistent with the hypothesis that they are a single-age population, with an inferred age of 0.1 to 1 Gyr. The luminosity function shows increasing numbers of blue clusters to the limit of our photometry, which reaches several magnitudes past the turnover predicted if the cluster population is identical to current Galactic globular clusters seen at a younger age. The blue clusters have a spatial distribution that is more centrally peaked than that of the red clusters. The individual clusters are slightly resolved, with core radii \u227e0.75 pc if they have modified Hubble profiles. We estimate the specific frequencies of the old and young populations and discuss the uncertainties in these estimates. We find that the specific frequency of the young population in NGC 1275 is currently larger than that of the old population and will remain so as the young population evolves, even if the majority of the low-mass clusters are eventually destroyed. If the young population formed during a previous merger, this suggests that mergers can increase the specific frequency of globular clusters in a galaxy. However, the presently observed young population likely contains too few clusters to have a significant impact on the overall specific frequency as it will be observed in the future.", "doi": "10.1086/300334", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1998-05", "series_number": "5", "volume": "115", "issue": "5", "pages": "1778-1790" }, { "id": "authors:h84yj-8zm65", "collection": "authors", "collection_id": "h84yj-8zm65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150122-083945622", "type": "article", "title": "Stellar populations in three outer fields of the Large Magellanic Cloud", "author": [ { "family_name": "Geha", "given_name": "Marla C.", "orcid": "0000-0002-7007-9725", "clpid": "Geha-M-C" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Cole", "given_name": "Andrew A.", "orcid": "0000-0003-0303-3855", "clpid": "Cole-A-A" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present Hubble Space Telescope photometry for three fields in the outer disk of the Large Magellanic Cloud (LMC) extending approximately 4 mag below the faintest main-sequence turnoff. We cannot detect any strongly significant differences in the stellar populations of the three fields based on the morphologies of the color-magnitude diagrams, the luminosity functions, and the relative numbers of stars in different evolutionary stages. Our observations therefore suggest similar star formation histories in these regions, although some variations are certainly allowed. The fields are located in two regions of the LMC: one is in the northeast and two are located in the northwest. Under the assumption of a common star formation history, we combine the three fields with ground-based data at the same location as one of the fields to improve statistics for the brightest stars. We compare this stellar population with those predicted from several simple star formation histories suggested in the literature, using a combination of the R-method of Bertelli et al. (1992) and comparisons with the observed luminosity function. The only model we consider that is not rejected by the observations is one in which the star formation rate is roughly constant for most of the LMC's history and then increases by a factor of 3 about 2 Gyr ago. Such a model has roughly equal numbers of stars older and younger than 4 Gyr, and thus is not dominated by young stars. This star formation history, combined with a closed-box chemical evolution model, is consistent with observations that the metallicity of the LMC has doubled in the past 2 Gyr.", "doi": "10.1086/300252", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1998-03", "series_number": "3", "volume": "115", "issue": "3", "pages": "1045-1056" }, { "id": "authors:nd45k-6s002", "collection": "authors", "collection_id": "nd45k-6s002", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141203-120216215", "type": "article", "title": "Asteroid Trails in Hubble Space Telescope1 WFPC2 Images: First Results", "author": [ { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Peters", "given_name": "Daniel P.", "clpid": "Peters-D-P" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Padgett", "given_name": "Deborah L.", "orcid": "0000-0001-5334-5107", "clpid": "Padgett-D-L" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Gallagher", "given_name": "Jay S.", "clpid": "Gallagher-J-S" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Grillmair", "given_name": "Carl", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John", "clpid": "Krist-J-E" }, { "family_name": "McMaster", "given_name": "Matthew", "clpid": "McMaster-M" }, { "family_name": "Meadows", "given_name": "Vikki", "clpid": "Meadows-V" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Ostrander", "given_name": "Eric", "clpid": "Ostrander-E" }, { "family_name": "Sahai", "given_name": "Raghvendra", "clpid": "Sahai-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James", "clpid": "Westphal-J-A" } ], "abstract": "Careful examination of 28,460 selected Wide Field and Planetary Camera 2 (WFPC2) long exposures from 1994, 1995, and early 1996 has revealed trails of 96 distinct moving objects. They have been reported to the International Astronomical Union's (IAU) Minor Planet Center for their asteroid database and a few have been identified with known asteroids and used to update their orbits. Most of the objects are new, as they are too faint to show up on ground-based surveys.\n\nThe trails often show a characteristic curvature due to the parallax induced by HST's orbital motion during the exposures. Using ephemerides for HST, the distance to each object can be directly determined from the parallax contribution to the trail shapes. Based on these distances, constraints on the orbits, and photometry of the trails (16", "doi": "10.1006/icar.1997.5873", "issn": "0019-1035", "publisher": "Elsevier", "publication": "Icarus", "publication_date": "1998-02", "series_number": "2", "volume": "131", "issue": "2", "pages": "261-282" }, { "id": "authors:hy1c5-t8v60", "collection": "authors", "collection_id": "hy1c5-t8v60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-095029948", "type": "article", "title": "Imaging of the Egg Nebula (CRL 2688) with WFPC2/HST: A history of age/post-AGB giant branch mass loss", "author": [ { "family_name": "Sahai", "given_name": "Raghvendra", "clpid": "Sahai-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Hester", "given_name": "J. J.", "clpid": "Hester-J-J" }, { "family_name": "Burrows", "given_name": "C. J.", "clpid": "Burrows-C-J" }, { "family_name": "Ballister", "given_name": "G. E.", "clpid": "Ballister-G-E" }, { "family_name": "Clarke", "given_name": "J. T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "D.", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "R. W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "J. S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "R. E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "J. G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "J. A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "P. A.", "clpid": "Scowen-P-A" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "The proto-planetary nebula, CRL 2688, has been imaged through a wideband filter centered at 606 nm (F606W) with the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope. CRL 2688 is the prototypical bipolar reflection nebula in which a star is surrounded by a dense, flattened cocoon of dust seen nearly edge-on and starlight escapes preferentially along the polar directions producing a pair of bright nebulosities, one above and one below the equatorial plane. We find a pair of radial \"searchlight beams\" emerging from within the dusty cocoon which intersect at the position expected for the central star when extrapolated inside the cocoon. The beams are crisscrossed by a large number of roughly round arcs with their center of curvature in the vicinity of the central star. The arcs are not systematically elongated along the polar axis of the nebula, as would be expected in the current model of CRL 2688 where the nebular density decreases with latitude. Our image directly shows the last ~ 13,000 yr history of mass ejection from the central star while it was on the tip of the asymptotic giant branch (AGE). We find that the average surface brightness varies as r^(-3.7), implying that the average mass-loss rate or the scattering opacity of the dust grains varies as r^(-0.7), i.e., one or both of these parameters have steadily increased with time. The temporal resolution of \u224825 yr in our images has provided direct evidence for episodic increases in the mass-loss rate by factors of ~2 or more, occurring every 150-450 yr, and lasting over periods of 75-200 yr. These irregularities in the mass-loss rate are roughly spherically symmetric. We have resolved the edges of the searchlight beams, as well as the peculiar structure of the inner region of the nebula (1\".5 < radius < 6\"). Our data require a new model for CRL 2688 in which the beams result from starlight escaping through a pair of nonuniform annular holes in the dust cocoon which are coaxial with the polar axis of the nebula. The holes have probably been generated by a young (less than 200 yr) high-velocity outflow which streams out through these holes and interacts with the surrounding dense AGE wind to produce the peculiar structure of the inner nebula. The cocoon contains dust grains of size about 0.6 \u00b5m, significantly larger than those in the extended nebula.", "doi": "10.1086/305121", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1998-01", "series_number": "1", "volume": "493", "issue": "1", "pages": "301-311" }, { "id": "authors:61ecd-4k041", "collection": "authors", "collection_id": "61ecd-4k041", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-152955114", "type": "article", "title": "Hubble Space Telescope observations of the Draco dwarf spheroidal galaxy", "author": [ { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Worthey", "given_name": "Guy", "clpid": "Worthey-G" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present an F606W-F814W color-magnitude diagram for the Draco dwarf spheroidal galaxy based on Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images. The luminosity function is well sampled to ~3 mag below the turnoff. We see no evidence for multiple turnoffs and conclude that, at least over the field of view of the WFPC2, star formation was primarily single-epoch. If the observed number of blue stragglers is due to extended star formation, then roughly 6% (upper limit) of the stars could be half as old as the bulk of the galaxy. The color difference between the red giant branch and the turnoff is consistent with an old population and is very similar to that observed in the old, metal-poor Galactic globular clusters M68 and M92. Despite its red horizontal branch, Draco appears to be older than M68 and M92 by 1.6 \u00b1 2.5 Gyr, lending support to the argument that the \"second parameter\" that governs horizontal-branch morphology must be something other than age. Draco's observed luminosity function is very similar to that of M68, and the derived initial mass function is consistent with that of the solar neighborhood.", "doi": "10.1086/300169", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1998-01", "series_number": "1", "volume": "115", "issue": "1", "pages": "144-151" }, { "id": "authors:qpxp9-1by60", "collection": "authors", "collection_id": "qpxp9-1by60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-083518694", "type": "article", "title": "Far-Ultraviolet Imaging of the Large Magellanic Cloud Populous Cluster NGC 1978 with WFPC2", "author": [ { "family_name": "Cole", "given_name": "Andrew A.", "orcid": "0000-0003-0303-3855", "clpid": "Cole-A-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have imaged the ~2.2 billion-year-old Large Magellanic Cloud populous cluster NGC 1978 in the far-ultraviolet and visible with the second Wide Field/Planetary Camera (WFPC2) on the Hubble Space Telescope. The far-ultraviolet images show a sparse stellar field with little apparent density enhancement in the cluster core. The visible images are dominated by the cluster's first-ascent and second-ascent red giants, which are completely invisible to the far-ultraviolet filter. No evidence for a hot horizontal branch population of core-helium-burning stars is seen; nor is there any apparent indication of a significant blue\nstraggler population. These results suggest that the presence of a rich, young population of field stars in the\nNGC 1978 region is responsible for the unusual location of the cluster in the integrated light color-color plots produced by IUE.", "doi": "10.1086/118616", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1997-11", "series_number": "5", "volume": "114", "issue": "5", "pages": "1945-1950" }, { "id": "authors:wfb8m-s9y94", "collection": "authors", "collection_id": "wfb8m-s9y94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200311-161942740", "type": "book_section", "title": "Wavefront sensing of atmospheric phase distortions at the Palomar 200-in. telescope and implications for adaptive optics", "author": [ { "family_name": "Bloemhof", "given_name": "E. E.", "clpid": "Bloemhof-E-E" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" } ], "contributor": [ { "family_name": "Bissonnette", "given_name": "Luc R.", "clpid": "Bissonnette-L-R" }, { "family_name": "Dainty", "given_name": "Christopher", "clpid": "Dainty-C" } ], "abstract": "Major efforts in astronomical instrumentation are now being made to apply the techniques of adaptive optics to the correction of phase distortions induced by the turbulent atmosphere and by quasi-static aberrations in telescopes themselves. Despite decades of study, the problem of atmospheric turbulence is still only partially understood. We have obtained video-rate (30 Hz) imaging of stellar clusters and of single-star phase distortions over the pupil of the 200\" Hale telescope on Palomar Mountain. These data show complex temporal and spatial behavior, with multiple components arising at a number of scale heights in the atmosphere; we hope to quantify this behavior to ensure the feasibility of adaptive optics at the Observatory. We have implemented different wavefront sensing techniques to measure aperture phase in wavefronts from single stars, including the classical Foucault test, which measures the local gradient of phase, and the recently-devised curvature sensing technique, which measures the second derivative of pupil phase and has formed the real-time wavefront sensor for some very productive astronomical adaptive optics. Our data, though not fast enough to capture all details of atmospheric phase fluctuations, provide important information regarding the capabilities that must be met by the adaptive optics system now being built for the 200\" telescope by a team at the Jet Propulsion Lab. We describe our data acquisition techniques, initial results from efforts to characterize the properties of the turbulent atmosphere at Palomar Mountain, and future plans to extract additional quantitative parameters of use for adaptive optics performance predictions.", "doi": "10.1117/12.283893", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "publication_date": "1997-09-23" }, { "id": "authors:yc637-4y612", "collection": "authors", "collection_id": "yc637-4y612", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-100522304", "type": "article", "title": "Hubble Space Telescope WFPC2 Images of Emission Nebulosity near XZ Tauri", "author": [ { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "XZ Tauri is a M3 V T Tauri star with a pre-main-sequence binary companion detected by infrared speckle interferometry at a projected separation of 0\".3 (about 40 AU). Previous ground-based observations of the system have shown bipolar emission nebulosity, including a possible jet knot. Images obtained with the Wide Field and Planetary Camera 2 on the Hubble Space Telescope show an elongated, filled bubble of emission nebulosity extending over 4\" to the north of the system which contains two or three compact knots. The source of the nebulosity is undetermined. For the first time, the components are separated in visible light, and the southern component (XZ Tau S) dominates the integrated light of the system. The reverse has been found to be true in the near-infrared. Thus we confirm that XZ Tauri belongs to the small class of young binaries with cool infrared companions.", "doi": "10.1086/304056", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1997-05-20", "series_number": "1", "volume": "481", "issue": "1", "pages": "447-451" }, { "id": "authors:y8tdd-x3396", "collection": "authors", "collection_id": "y8tdd-x3396", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-101615749", "type": "article", "title": "The star-formation history in the vicinity of NGC 1866 in the Large Magellanic Cloud", "author": [ { "family_name": "Stappers", "given_name": "Benjamin W.", "clpid": "Stappers-B-W" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Sebo", "given_name": "Kim M.", "clpid": "Sebo-K-M" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "To expand on the recent single WFPC2 field obtained in the vicinity of this cluster, we have measured the luminosity function in a one-third by one-half degree held in the LMC with the 40-in. telescope at Siding Spring Observatory. Combining our results with recent 4-m and WFPC2 observations, we examine the constraints on the star-formation history of the held from 10^8 to 10^(10) years ago. The simple model derived from the WFPC2 data with an increase in the star-formation rate ~3 Gyr ago fits the combined data. However, this rate increase seems to have been unique. This event notwithstanding, the smooth luminosity function from V=16 to V=22 suggests steady star formation rather than a star-formation history dominated by intense bursts.", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1997-03", "series_number": "733", "volume": "109", "issue": "733", "pages": "292-296" }, { "id": "authors:cy31t-t4b22", "collection": "authors", "collection_id": "cy31t-t4b22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-075134326", "type": "article", "title": "Stellar Populations in the Dwarf Elliptical Galaxy NGC 147", "author": [ { "family_name": "Han", "given_name": "M.", "clpid": "Han-M" }, { "family_name": "Hoessel", "given_name": "J. G.", "clpid": "Hoessel-J-G" }, { "family_name": "Gallagher", "given_name": "J. S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J" }, { "family_name": "Stetson", "given_name": "P. B.", "orcid": "0000-0001-6074-6830", "clpid": "Stetson-P-B" }, { "family_name": "Trauger", "given_name": "J.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "G. E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "C.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "J.", "clpid": "Clarke-J" }, { "family_name": "Crisp", "given_name": "D.", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "R.", "clpid": "Griffiths-R" }, { "family_name": "Grillmair", "given_name": "C.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Hester", "given_name": "J.", "clpid": "Hester-J" }, { "family_name": "Krist", "given_name": "J.", "clpid": "Krist-J" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "P.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "K.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Watson", "given_name": "A.", "clpid": "Watson-A" }, { "family_name": "Westphal", "given_name": "J.", "clpid": "Westphal-J-A" } ], "abstract": "Deep V and I CCD images in a central and an outer field of the Local Group dwarf elliptical galaxy NGC 147 have been obtained with the Wide Field and Planetary Camera-2 (WFPC2) on board of the Hubble Space Telescope. The color-magnitude diagram shows a number of interesting features, including a well defined red giant branch (RGB), a red horizontal branch (HB), a strong red clump, and a small number of\nextended asymptotic giant branch (EAGB) stars. A mean distance modulus of (m- M)_0=24.39 is derived based on both the HB and the RGB tip brightness. The metallicity [Fe/H] as determined from the RGB color has a mean value of -0.91 in the central field, and -1.0 in the outer field; and the outer field shows a weak tendency of increasing metallicity with galactocentric radius. A metallicity dispersion is also present in the galaxy, and it shows a clear radial variation in the sense that a larger dispersion is seen at smaller radii. The small population of EAGB stars indicates the presence of intermediate-aged (several Gyr) stars in the\ngalaxy, while the absence of the main sequence stars with M v< 1 shows that star formation ceased at least 1 Gyr ago. The distribution of the EAGB stars indicates that the younger stars are more centrally concentrated than the majority of older stars. A similar age gradient is also implied by the relative distribution of the HB stars, which appear to be more populous at larger radii. These results are considered within the context of theoretical models for the evolution of dwarf elliptical galaxies.", "doi": "10.1086/118316", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1997-03", "series_number": "3", "volume": "113", "issue": "3", "pages": "1001-1010" }, { "id": "authors:j0t0y-k8659", "collection": "authors", "collection_id": "j0t0y-k8659", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-151615843", "type": "article", "title": "Stellar populations in the Large Magellanic Cloud: Evidence for a significant number of older stars or a steeper IMF?", "author": [ { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present deep photometry obtained with the HST in an outer LMC field. A well-defined main sequence is seen down to V > 26. We derive a luminosity function from the data and use it to constrain the IMF and the star formation history. We derive limits on the IMF slope, \u0251(with dN/\u221ddM^\u0251), from stars on the main sequence which are fainter than the oldest turnoff. For most choices of star formation history and metallicity, we derive slopes which are consistent the Salpeter (\u0251= -2.35) or local solar neighborhood IMF, although the preferred values are steeper. We can rule out IMF slopes shallower than -1.6 and steeper than -3.1 for the mass range 0.6\u227eM\u227e1.1 M_\u2609. Assuming a Salpeter IMF over the entire observed mass range, we derive star formation histories from the entire luminosity function, which covers the mass range 0.6\u227eM\u227e1.1 3 M_\u2609. We find that the luminosity function is inconsistent with the scenario in which the bulk of the field stars in the LMC are younger than 4 Gyr. Instead, we find that there must be a comparable number of stars older and younger than 4 Gyr. Our best model has a star formation rate which is roughly constant for 10 Gyr then increases by about a factor of three for the past 2 Gyr. Such a model is also roughly consistent with the distribution of stars in the color-magnitude diagram. Similar model parameters are derived if we adopt the Kroupa, Tout, and Gilmore solar neighborhood LMF instead of a Salpeter slope. Alternatively, we can fit the luminosity function with a predominantly young population if we use a steeper single power law IMF slope with \u0251 ~-2.75 over the entire range of observed masses.", "doi": "10.1086/118284", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1997-02", "series_number": "2", "volume": "113", "issue": "2", "pages": "656-668" }, { "id": "authors:4xxmp-pe243", "collection": "authors", "collection_id": "4xxmp-pe243", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-141320896", "type": "book_section", "title": "Hubble Space Telescope Observations of the Draco Dwarf Spheroidal", "book_title": "The Nature of Elliptical Galaxies", "author": [ { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Worthey", "given_name": "Guy", "clpid": "Worthey-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Trauger", "given_name": "J.", "clpid": "Trauger-J" }, { "family_name": "Ballester", "given_name": "G. E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "C.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "J.", "clpid": "Clarke-J" }, { "family_name": "Crisp", "given_name": "D.", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "R.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J.", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "J. G.", "clpid": "Hoessel-J-G" }, { "family_name": "Krist", "given_name": "J.", "clpid": "Krist-J" }, { "family_name": "Scowen", "given_name": "P.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "K.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Watson", "given_name": "A.", "clpid": "Watson-A" }, { "family_name": "Westphal", "given_name": "J.", "clpid": "Westphal-J-A" } ], "contributor": [ { "family_name": "Arnaboldi", "given_name": "M.", "clpid": "Arnaboldi-M" }, { "family_name": "da Costa", "given_name": "G. S.", "clpid": "da-Costa-G-S" }, { "family_name": "Saha", "given_name": "P.", "clpid": "Saha-P" } ], "abstract": "The color-magnitude (CM) diagram of the Draco dwarf spheroidal was first\nstudied by Baade & Swope (1961). In addition to finding a general similarity\nto the CM-diagrams of metal-poor globular clusters, they also detected the\nanomalous Cepheids and broad giant branch which are characteristic of dwarf\nspheroidals. The best ground-based CCD CM diagrams of the Draco dwarf\nspheroidal to date have been presented by Stetson, Vandenberg, & McClure\n(1985) and Carney & Seitzer (1986, hereafter CS86). Here we describe the first\nresults of an HST program to investigate the stellar population of this galaxy.", "isbn": "1-886733-36-8", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1997", "pages": "306-307" }, { "id": "authors:0kcxx-4cn89", "collection": "authors", "collection_id": "0kcxx-4cn89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-093813019", "type": "article", "title": "Hubble space telescope observations of the disk and jet of HH 30", "author": [ { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "HH 30 in Taurus has been imaged with the Hubble Space Telescope WFPC2. The images show in reflected light a flared disk with a radius of about 250 AU that obscures the protostar. The disk resembles detailed accretion disk models that constrain its density distribution and show that its inclination is less than 10 degrees. There are bipolar emission-line jets perpendicular to the disk, a very clear demonstration of the standard paradigm for accretion disk and jet systems. However, asymmetries in the light distribution show that the disk has not completely settled into a quasi-equilibrium accretion state, or that some of the observed scattering is from an asymmetric envelope. The emission-line jet itself is resolved into a number of knots with typical lengths and separations of 0\".4, much smaller and more numerous than indicated by lower resolution ground-based studies. There are indications of still finer structures in the jet all the way to the resolution limit of 0\".1. The knots have proper motions ranging from 100 to 300 km s^(-1) and are therefore generated at the surprisingly high rate of about 0.4 knots per jet per year. The jet appears to be collimated within a cone of opening angle 3\u00ba and can be seen to within 30 AU of the star. Both single- and multiple-scattering disk models have a range of possible solutions, but by requiring pressure support and temperature equilibrium, a self-consistent model emerges. There is evidence for pressure support because the disk appears to have a Gaussian height profile. The temperature at each point in the disk is determined by the disk geometry, which in turn fixes the temperature in a self-consistent manner. The extinction to the protostar is unknown but constrained to be greater than 24 mag. The optical properties of the scattering grains in the disk are determined and found to imply a large scattering asymmetry, but they seem to follow the interstellar reddening law. The absolute magnitude and colors of the unseen protostar, which has a brightness in the I bandpass of about 0.16 times solar and is very red, are obtained. The disk mass is about 0.006 times solar and has an expected lifetime of about 10^5 yr.", "doi": "10.1086/178156", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-12-10", "series_number": "1", "volume": "473", "issue": "1", "pages": "437-451" }, { "id": "authors:gzj4e-cvm58", "collection": "authors", "collection_id": "gzj4e-cvm58", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150120-115446337", "type": "article", "title": "Far-Ultraviolet Imaging of Jupiter's Aurora and the Io \"Footprint\"", "author": [ { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Trauger", "given_name": "John", "clpid": "Trauger-J-T" }, { "family_name": "Evans", "given_name": "Robin", "clpid": "Evans-R-W" }, { "family_name": "Connerney", "given_name": "J. E. P.", "orcid": "0000-0001-7478-6462", "clpid": "Connerney-J-E-P" }, { "family_name": "Stapelfeldt", "given_name": "K.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Feldman", "given_name": "Paul D.", "clpid": "Feldman-P-D" }, { "family_name": "Burrows", "given_name": "J.", "clpid": "Burrows-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Meadows", "given_name": "Vikki", "clpid": "Meadows-V" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Far-ultraviolet images of Jupiter from the Hubble Space Telescope Wide Field Planetary Camera 2 reveal polar auroral emissions at 300 kilometer resolution and three times higher sensitivity than previously achieved. Persistent features include a main oval containing most of the emission and magnetically connected to the middle magnetosphere, diffuse and variable emissions poleward of the main oval, and discrete emission from Io's magnetic footprint equatorward of the oval. The auroral emissions are variable, exhibit magnetic conjugacy, and are visible above the planet limb. All emissions approximately co-rotate with Jupiter except the Io \"footprint,\" which is fixed along Io's magnetic flux tube.", "doi": "10.1126/science.274.5286.404", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1996-10-18", "series_number": "5286", "volume": "274", "issue": "5286", "pages": "404-409" }, { "id": "authors:r8k3b-sgg65", "collection": "authors", "collection_id": "r8k3b-sgg65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-084207968", "type": "article", "title": "Time-Resolved Observations of Jupiter's Far-Ultraviolet Aurora", "author": [ { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Harris", "given_name": "Walter M.", "clpid": "Harris-W-M" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Burgh", "given_name": "Eric B.", "clpid": "Burgh-E-B" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Meadows", "given_name": "Vikki", "clpid": "Meadows-V" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Sahai", "given_name": "Raghvendra", "clpid": "Sahai-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Simultaneous imaging and spectroscopic observations of Jupiter's far-ultraviolet aurora covering half a jovian rotation were made on 31 May 1994. The Hubble Space Telescope Wide Field Planetary Camera 2 images revealed dramatic and rapidly changing auroral features, including discrete longitudinal structures along the auroral ovals, with variable contrast; a poleward offset in a north oval sector, showing equatorward motion near dusk; emissions polewards of the ovals, apparently co-rotating; and a bright event developing near the dawn limb. Viewing geometry effects explain the rotational intensity modulation observed by the International Ultraviolet Explorer, without intrinsic longitudinal asymmetries.", "doi": "10.1126/science.274.5286.409", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1996-10-18", "series_number": "5286", "volume": "274", "issue": "5286", "pages": "409-413" }, { "id": "authors:txnf6-6kg77", "collection": "authors", "collection_id": "txnf6-6kg77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150115-090204449", "type": "article", "title": "WFPC2 observations of the cooling flow elliptical in Abell 1795", "author": [ { "family_name": "Pinkney", "given_name": "Jason", "clpid": "Pinkey-J" }, { "family_name": "Holtzman", "given_name": "Jon", "clpid": "Holtzman-J-A" }, { "family_name": "Garasi", "given_name": "Christopher", "clpid": "Garasi-C" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present WFPC2 images of the core of the cooling flow cD galaxy in Abell 1795. An irregular, asymmetric dust lane extends 7 h^(-1)/75 kpc in projection to the north-northwest. The dust shares the morphology observed in the Ha and excess UV emission. We see both diffuse and knotty blue emission around the dust lane, especially at the ends. The dust and emission features lie on the edge of the radio lobes, suggesting star formation induced by the radio source or the deflection of the radio jets off of preexisting dust and gas. We measure an apparent R(V) significantly less than 3.1, implying that the extinction law is not Galactic in the dust lane, or the presence of line emission that is proportional to the extinction. The dust mass is at least 2 x 10^5 h^(-2)/75 M_\u2609 and is more likely to be 6.5 x 10^5 h^(-2)/75 M_\u2609.", "doi": "10.1086/310219", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-09-01", "series_number": "1", "volume": "468", "issue": "1", "pages": "L13-L16" }, { "id": "authors:chbn4-85j86", "collection": "authors", "collection_id": "chbn4-85j86", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-112245590", "type": "article", "title": "Main-Sequence Stars and the Star Formation History of the Outer Disk in the Large Magellanic Cloud", "author": [ { "family_name": "Gallagher", "given_name": "J.", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Mould", "given_name": "J. R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "De Feijter", "given_name": "E.", "clpid": "De-Feijter-E" }, { "family_name": "Holtzman", "given_name": "J.", "clpid": "Holtzman-J-A" }, { "family_name": "Stappers", "given_name": "B.", "clpid": "Stappers-B-W" }, { "family_name": "Watson", "given_name": "A.", "clpid": "Watson-A-T" }, { "family_name": "Trauger", "given_name": "J.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "G. E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "C. J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "S.", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "J. T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "D.", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "R. E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. J.", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "J.", "clpid": "Hoessel-J-G" }, { "family_name": "Krist", "given_name": "J.", "clpid": "Krist-J" }, { "family_name": "Matthews", "given_name": "L. D.", "clpid": "Matthews-L-D" }, { "family_name": "Scowen", "given_name": "P. A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "K. R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Using the Wide Field Planetary Camera 2 on the Hubble Space Telescope, we have obtained a deep color-magnitude diagram in V- and I-band equivalents for more than 2000 stars in a patch of the outer disk of the Large Magellanic Cloud LMC). Aperture photometry is feasible from these data with good\nsignal-to-noise ratio for stars with V \u2264 25, which allows us for the first time to construct a color magnitude diagram for LMC disk stars on the lower main sequence, extending beyond the oldest main sequence turnoff point. We analyze the structure of the main-sequence band and overall morphology of the color-magnitude diagram to obtain a star formation history for the region. A comparison between\nthe distribution of stars across the main-sequence band for M_v \u2264 4 and a stellar population model constrains\nhistorical star formation rates within the past 3 Gyr. The stellar populations in this region sample the outer LMC disk for stars with ages of 1 Gyr or older that have had time to spatially mix. The structure of the main-sequence band requires that star formation occurred at a roughly constant rate during most of the past \u2248 3 Gyr. However, the distribution of subgiant stars indicate that a pronounced\npeak in the star formation rate likely occurred about 2 Gyr ago, prior to which the star formation rate had not been enhanced for several Gyr. Studies over timescales of more than 3 Gyr require a separation of the effects of star formation history and the chemical evolution on the LMC color-magnitude diagrams, which is difficult to achieve without additional constraints. If lower main-sequence stars in the LMC have moderate metallicities, then the age for most LMC disk stars is less than about 8 Gyr.", "doi": "10.1086/177546", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-08-01", "volume": "466", "pages": "732-741" }, { "id": "authors:q89mc-rz721", "collection": "authors", "collection_id": "q89mc-rz721", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-095601114", "type": "article", "title": "Visible and Far-Ultraviolet WFPC2 Imaging of the Nucleus of the Galaxy NGC 205", "author": [ { "family_name": "Jones", "given_name": "D. Heath", "clpid": "Jones-D-H" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Grillmair", "given_name": "Carl", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have imaged the nucleus of NGC 205 through the F555W and F160BW filters of WFPC2 on the high-resolution planetary camera (PC). The nucleus consists of a resolved cluster of stars extending 7\" X 6\".\nThe projected radial distribution of surface brightness can be fitted by a Hubble law with a small core of FWHM 214 x 190 mas (0.74 x 0.66 pc). We find that the nucleus of NGC 205 shares a number of characteristics with globular clusters. Absolute photometry is also presented in a half-arcsec aperture and is found to verify the amount of UV upturn observed in the spectral energy distribution of the nucleus by others (e.g., Bertola et al. 1995).\nOf the hypotheses available to explain the origin of the nucleus, the observations are most consistent with its being an intermediate age cluster. The most likely scenarios are that it is a either a star cluster whose orbit has decayed-therefore drawing it to rest at the galaxy center-or a cluster that has formed as the repository of the gas from generations of star formation.\nTogether with the ground-based measurement of a low-velocity dispersion, the small core radius implies a 107 yr relaxation time, suggesting the cluster core may have collapsed. An upper limit of 9 x 10^4 M_\u2609 can be put on the mass of any central black hole.", "doi": "10.1086/177547", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-08-01", "series_number": "2", "volume": "466", "issue": "2", "pages": "742-749" }, { "id": "authors:jjxfc-x8y17", "collection": "authors", "collection_id": "jjxfc-x8y17", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-091207056", "type": "article", "title": "Star Clusters in Interacting and Cooling Flow Galaxies", "author": [ { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Two interacting galaxies and four central galaxies in cooling flow clusters were observed with the Hubble\nSpace Telescope to look for young compact massive star clusters. The two interacting galaxies, NGC 3597 and NGC 6052, show clear evidence for resolved bright blue clusters that are likely to be comparable in mass to Galactic globulars based on their colors and brightnesses. In NGC 3597, the clusters have physical sizes comparable to Galactic globulars. In NGC 6052, there are a few compact clusters, but most appear more extended. No such objects were seen in three of the four cooling flow galaxies. The central galaxy in Abell 1795 may have several massive blue clusters, but its distance prevents us from knowing how compact they are.", "doi": "10.1086/118025", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1996-08", "series_number": "2", "volume": "112", "issue": "2", "pages": "416-430" }, { "id": "authors:ydke1-xcd36", "collection": "authors", "collection_id": "ydke1-xcd36", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-151905741", "type": "article", "title": "The Discovery of Young, Luminous, Compact Stellar Clusters in the Starburst Galaxy NGC 253", "author": [ { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We report the discovery of four young, luminous, compact stellar clusters in the central region of the\nstarburst spiral galaxy NGC 253. One cluster has an intrinsic M_v of about -15 or brighter, an inferred mass\nin excess of 1.5X10^6 M_\u2609, assuming a Salpeter IMF from 0.08M_\u2609 to l00M_\u2609, and is resolved with a half-light radius of about 2.5 parsec if it has a radial profile similar to a Galactic globular cluster. The others\nhave intrinsic M_v of about -11 or brighter, inferred masses in excess of 5 X 10^4 M_\u2609, and are similarly\ncompact. These clusters are excellent candidate young globular clusters. The brighter cluster is similar in\nluminosity, inferred mass, and compactness to the super star clusters found in other sites of ongoing or recent intense star formation. The location of these clusters in the midst of a starburst region suggests that intense star formation may be a key ingredient in their creation. There are hints that these candidate young globular clusters may be forming with a high specific frequency.", "doi": "10.1086/118032", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1996-08", "series_number": "2", "volume": "112", "issue": "2", "pages": "534-544" }, { "id": "authors:e18fm-ahq35", "collection": "authors", "collection_id": "e18fm-ahq35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-094315944", "type": "article", "title": "Low-Mass Stars in an Outer Field in NGC 6397", "author": [ { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have imaged a field 10' from the center of the globular cluster NGC 6397 in the visible and I bands with WFPC2 on the \u0397 ST. At a level which is severely limited by counting statistics in the small area so far studied, this field is richer in dwarfs with />21.5 than the 4:6 radius parallel field discussed by Paresce and colleagues. This indicates that the dynamical process of mass segregation is occurring in the cluster.", "doi": "10.1086/133785", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1996-08", "series_number": "726", "volume": "108", "issue": "726", "pages": "682-687" }, { "id": "authors:2sqgd-9p588", "collection": "authors", "collection_id": "2sqgd-9p588", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-135350590", "type": "article", "title": "Detection of the Tip of the Red Giant Branch in NGC 5128", "author": [ { "family_name": "Soria", "given_name": "Roberto", "orcid": "0000-0002-4622-796X", "clpid": "Soria-Roberto" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present a color-magnitude diagram of more than 10,000 stars in the halo of the galaxy NGC 5128 (Centaurus A), based on WFPC2 images through V-band and I-band filters. The position of the red giant branch (RGB) stars is compared with the loci of the red giant branch in six well-studied globular clusters and in the dwarf elliptical galaxy NGC 185; the tip of the RGB is signalled by an observed turn-up in the luminosity function at I\u224324.1 \u00b1 0.1 mag; this yields a distance modulus (m - M)_0 = 27.8 \u00b1 0.2 for NGC 5128 (i.e., a distance of 3.6 \u00b1 0.2 Mpc), in agreement with previous determinations based on the planetary nebulae luminosity function and on the surface brightness fluctuations technique. The presence of an intermediate-age stellar population (~5 Gyr) is suggested by the luminosity function of the asymptotic giant branch stars, extending up to I= 22.6 mag (for V - I > 2) and M_(bot) ~ -5 mag; however, the number of these stars constrains the intermediate-age stellar population in the halo of NGC 5128 to be less than ~ 10% of the total. The color distribution at constant I magnitude, albeit affected by the completeness level of our sample, strongly suggests a mean value of [Fe/H] > -0.9 dex, possibly similar to the value found in M31 and higher than that observed in NGC 185. Like the M31 halo, the halo of NGC 5128 exhibits a broad range of levels of chemical enrichment.", "doi": "10.1086/177403", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-07-01", "series_number": "1", "volume": "465", "issue": "1", "pages": "79-90" }, { "id": "authors:4bhy2-nkt06", "collection": "authors", "collection_id": "4bhy2-nkt06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-085147789", "type": "article", "title": "Hubble Space Telescope WFPC2 Imaging of M16: Photoevaporation and Emerging Young Stellar Objects", "author": [ { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Sankrit", "given_name": "Ravi", "clpid": "Sankrit-R" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Ajhar", "given_name": "Edward A.", "clpid": "Ajhar-E-A" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Code", "given_name": "Arthur", "clpid": "Code-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Ewald", "given_name": "Shawn P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Faber", "given_name": "Sandra M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Grillmair", "given_name": "Carl J.", "orcid": "0000-0003-4072-169X", "clpid": "Grillmair-C-J" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Hunter", "given_name": "Deidre A.", "orcid": "0000-0002-3322-9798", "clpid": "Hunter-D-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "C. Roger", "clpid": "Lynds-C-R" }, { "family_name": "Monet", "given_name": "David G.", "clpid": "Monet-D-G" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Seidelmann", "given_name": "Kenneth P.", "clpid": "Seidelmann-P-K" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present Hubble Space Telescope WFPC2 images of elephant trunks in the H II region M16. There are three principle results of this study. First, the morphology and stratified ionization structure of the interface between the dense molecular material and the interior of the H II region is well understood in terms of photoionization of a photoevaporative flow. Photoionization models of an empirical density profile capture the essential features of the observations, including the extremely localized region of [S II] emission at the interface and the observed offset between emission peaks in lower and higher ionization lines. The details of this structure are found to be a sensitive function both of the density profile of the interface and of the shape of the ionizing continuum. Interpretation of the interaction of the photoevaporative flow with gas in the interior of the nebula supports the view that much of the emission from H II regions may arise in such flows. Photoionization of photoevaporative flows may provide a useful paradigm for interpreting a wide\nrange of observations of H II regions. Second, we report the discovery of a population of small cometary globules that are being uncovered as the main bodies of the elephant trunks are dispersed. Several lines of evidence connect these globules to ongoing star formation, including the association of a number of globules with stellar objects seen in IR images of M16 or in the continuum HST images themselves. We refer to these structures as evaporating gaseous globules, or \"EGGs.\" These appear to be the same type of object as the nebular condensations seen previously in M42. The primary difference between the two cases is that in M16 we are seeing the objects from the side, while in M42 the objects are seen more nearly face-on against the backdrop of the ionized face of the molecular cloud. We find that the \"evaporating globule\" interpretation naturally accounts for the properties of objects in both nebulae, while avoiding serious difficulties with the competing \"evaporating disk\" model previously applied to the objects in M42. More generally, we find that disk-like structures are relatively rare in either nebula. Third, the data indicate that photoevaporation may have uncovered many EGGs while the stellar objects in them were still accreting\nmass, thereby freezing the mass distribution of the protostars at an early stage in their evolution. We conclude that the masses of stars in the cluster environment in M16 are generally determined not by the\nonset of stellar winds, as in more isolated regions of star formation, but rather by disruption of the star forming environment by the nearby O stars.", "doi": "10.1086/117968", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1996-06", "series_number": "6", "volume": "111", "issue": "6", "pages": "2349-2532" }, { "id": "authors:dy4av-5gx15", "collection": "authors", "collection_id": "dy4av-5gx15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-133708737", "type": "article", "title": "Far-Ultraviolet Imaging of the Globular Cluster NGC 7099 with the Second Wide-Field and Planetary Camera", "author": [ { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have imaged the globular cluster NGC 7099 in the far-UV and visible with WFPC2 on the Hubble Space Telescope. Our far-UV images show a sparsely populated and fully resolved central region. The far-UV to visible color-magnitude diagram of these stars shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal branch star; the center of the cluster harbors four luminous blue stragglers. Far-UV images do not show any singularly steep density gradient at small radii among the horizontal branch stars of this post-core-collapse cluster.", "doi": "10.1086/177100", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-04-20", "series_number": "2", "volume": "461", "issue": "2", "pages": "762-766" }, { "id": "authors:epkn0-n4x65", "collection": "authors", "collection_id": "epkn0-n4x65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-132023906", "type": "article", "title": "WFPC2 Studies of the Crab Nebula. III. Magnetic Rayleigh-Taylor Instabilities and the Origin of the Filaments", "author": [ { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Stone", "given_name": "James M.", "orcid": "0000-0003-0454-3718", "clpid": "Stone-J-M" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Jun", "given_name": "Byung-Il", "clpid": "Jun-Byung-Il" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Norman", "given_name": "Michael L.", "clpid": "Norman-M-L" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John", "clpid": "Krist-J-E" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Sankrit", "given_name": "Ravi", "clpid": "Sankrit-R" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Recently obtained Hubble Space Telescope WFPC2 images of the Crab Nebula show that the emission-line filaments are dominated by structures that morphologically appear to be the result of magnetic Rayleigh Taylor (R-T) instabilities at the interface between the pulsar-driven synchrotron nebula and a shell of swept up ejecta. We replace this morphological argument with a quantitative treatment of the growth rate and characteristic wavelength of such instabilities. Using published data on the rate of expansion of the synchrotron nebula and the density of the ejecta, together with a wavelength for the instability measured from the WFPC2 images, we calculate a magnetic field strength of ~540 \u00b5G. This is within a factor of 2 of the canonical minimum energy equipartition field of 300 \u00b5G, and probably closer than that to a more realistic estimate\nof the field at the edge of the Crab. Comparison of the detailed morphology and ionization structure of the R-T fingers in the Crab with recent magnetohydrodynamical simulations which follow the development of magnetic R-T instabilities into the nonlinear regime is used to establish a sequence of filament properties which are determined by the density of the shell of swept-up ejecta at the edge of the synchrotron nebula. When the density is below a critical value, the interface is stable. For somewhat higher densities R-T instabilities grow, but the field, which becomes aligned along the length of the R-T fingers, is strong enough to prevent the development of secondary Kelvin Helmholtz (K-H) instabilities as the finger falls through the lighter medium. At higher densities these K-H instabilities develop, but the field is still strong enough to maintain a long streamer-like connection between the head of the filament and the shell. In a few cases, the density of the shell is high enough that the magnetic field is unable to prevent the fragmentation of R-T fingers, and the structure becomes more characteristic of a nonmagnetic R-T instability. The magnetic field is oriented along the length of an R-T finger, so material is free to \"pour\" into the finger from above. In equilibrium, gradients in thermal pressure and effective gravity must balance along field lines. As a result, loss of pressure support in the fingers due to cooling enhances the flow of material into the fingers, \"siphoning\" gas into the finger from above. If an extended remnant of ejecta surrounds the visible extent of the Crab, as has been suggested frequently, then the synchrotron nebula is expanding through this extended remnant, sweeping up ejecta as it goes. R-T instabilities channel this swept-up ejecta into the hierarchy of dense visible filaments. It seems likely that the current system of filaments originated as a result of R-T instabilities as the synchrotron nebula expanded out through more uniformly distributed ejecta. If an extended remnant remains today, then filament formation is an ongoing process.\nThe ionization structure of filaments is also found to change in a systematic way as a function of the relative\nimportance of the magnetic field and the mass density. Filaments which are dominated by the magnetic field are confined by the field and have sharp, well defined edges. Filaments in which the magnetic field is less dominant consist of high-density, low-ionization cores embedded within more extended high-ionization material. This confirms a previous suggestion that variations in magnetic confinement are an important caveat to published interpretations of spectra of Crab filaments.", "doi": "10.1086/176643", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1996-01-01", "series_number": "1", "volume": "456", "issue": "1", "pages": "225-233" }, { "id": "authors:87try-jan81", "collection": "authors", "collection_id": "87try-jan81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-071549312", "type": "article", "title": "Hubble Space Telescope Observations of the SN 1987A Triple Ring Nebula", "author": [ { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Krist", "given_name": "John", "clpid": "Krist-J-E" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Sahai", "given_name": "Raghvendra", "clpid": "Sahai-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have observed SN 1987A with the optically corrected WFPC2 on the Hubble Space Telescope both in emission lines and in the UV and optical continuum. The previously observed outer nebular structure is shown to be part of two closed unresolved loops. These loops were flash-ionized by the supernova itself. They are not caused by limb brightening of an hourglass shell produced by the interaction of the winds from the progenitor. The inner ring is seen to be extended and may be connected to the new outer rings by sheets of material. However, beyond the outer rings, emission is not seen, implying a very low density (n < 10) for the outer hourglass shell if it exists. The new outer rings are unresolved, and this together with their observed brightness implies a density n > 1000. This density contrast of at least 100 is difficult to reconcile with the conventional picture of the progenitor evolution. Two models for the rings are presented, but each is deficient in important respects. A proper understanding of this system will require new physical insight.", "doi": "10.1086/176339", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-10-20", "series_number": "2", "volume": "452", "issue": "2", "pages": "680-684" }, { "id": "authors:zgmzm-5my75", "collection": "authors", "collection_id": "zgmzm-5my75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-154728719", "type": "article", "title": "WFPC2 Imaging of the Circumstellar Nebulosity of HL Tauri", "author": [ { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Planetary camera images of HL Tauri have been obtained through V-, R-, and I-band filters using the Wide Field and Planetary Camera 2 aboard the refurbished Hubble Space Telescope. These images show that HL Tauri is entirely reflection nebulosity at optical wavelengths, with no optical star visible to a limiting magnitude of V = 25.5. The optical nebula extends northeast of the stellar position along the direction of HL Tau's optical jet and has an unusual C-shaped morphology. The bright core of the nebula is only 1\" in size and is centered only 1\".2 from the actual stellar position. We estimate that visual extinction toward the unseen point source is at least 22 mag and that the stellar photospheric luminosity must be at least 3 L_\u2609. These findings corroborate other evidence that this star is significantly younger and more embedded than typical T Tauri stars.", "doi": "10.1086/176106", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-08-20", "series_number": "2", "volume": "449", "issue": "2", "pages": "888-893" }, { "id": "authors:7npza-xna59", "collection": "authors", "collection_id": "7npza-xna59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-134624888", "type": "article", "title": "WFPC2 Studies of the Crab Nebula. I. HST and ROSAT Imaging of the Synchrotron Nebula", "author": [ { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Sankrit", "given_name": "Ravit", "clpid": "Sankrit-R" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Watson", "given_name": "Alan", "clpid": "Watson-A-M" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Krist", "given_name": "John", "clpid": "Krist-J-E" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present images of the Crab synchrotron nebula obtained with the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope. These data are compared with ROSAT HRI images, and with 0':5 resolution Canada-France-Hawaii Telescope (CFHT) images previously published by van den Bergh & Pritchet (1989). These data strengthen the emerging picture of the Crab as a cylindrically symmetrical\nobject with an axis running southeast to northwest, and inclined by ~20\u00b0-30\u00b0 with respect to the plane of the sky. Identification of structure very near to the pulsar which shares this symmetry helps to better establish the link between the symmetry axis of the nebula and the spin axis of the pulsar. We report the discovery of a bright knot of visible emission located 0\u00ba.65 to the southeast of the pulsar, along the axis of the system. This knot and a second knot 3\".8 from the pulsar appear to be present but not well resolved in the 1988 CFHT image, indicating that they are persistent structures. The inner knot is interpreted as a shock in the pulsar wind ~ 1500 AU above the pole of the pulsar. No corresponding knots are seen to the northwest of the pulsar, which may indicate that the characteristics of the wind from the two poles are not symmetrical. The closest of the \"wisps\" to the northwest of the pulsar appear to close into a ringlike \"halo\" encircling the axis of the nebula. The wisps are resolved, with widths of ~ 0\".2. This allows\u00b7 calculation of their volumes and volume emissivities, and in turn their equipartition fields and pressures. Equipartition \npressures calculated for the knots and wisps are typically 10 to as much as 80 times the equipartition pressure\ncalculated for the nebula as a whole. The wisps show significant substructure which changed considerably\nbetween 1988 and 1994. Previous reports of relativistic motions of the wisps were probably due to changes in\nthe unresolved substructure of these features. Comparison of the CFHT and WFPC2 images show remarkable changes in the inner nebula, but inferences about physical conditions based on this comparison are limited by the resolution of the CFHT data and the long 5 year baseline between the images. The structure of the nebula in 1994 may be inconsistent with the recent model by Gallant & Arons (1994). Very fine fibrous texture visible in the WFPC2 image follows the structure of the X-ray torus. A puzzling\nanticorrelation is seen between the X-ray and visible surface brightness through part of the torus. Long contiguous low contrast features with widths of ~ 1\"-2\" are seen to run throughout the volume of the nebula. These features are seen to move outward through the nebula at velocities in excess of homologous expansion. These features trace the magnetic structure of the nebula; they are probably due to differences in emissivity accompanying varying degrees of departure from equipartition at roughly constant total pressure. Visible fibers \"drape over\" and appear to expand away from an X-ray counterjet to the northwest of the pulsar, supporting the interpretation of the counterjet as a directed flow of energy along the symmetry axis of the nebula. Other associations are also seen between X-ray and visible structures, including X-ray emission surrounding the east and west bays. An association is proposed between the observed structure of the nebula and different latitude zones found in models of winds from partially oblique rotators. We concur with previous suggestions that the X-ray torus and the sharp visible fibers associated with it mark a shock at r_s ~ 1.2 x 10^(18) cm in an equatorial striped magnetic wind. The halo and anvil arise at a distance of ~ 1.4 x 10^(17) cm from the pulsar in a helically polarized wind at latitudes greater than about 35\u00b0. Well collimated polar jets may be responsible for the knots to the southeast of the pulsar and for the jet and counterjet seen at X-ray and visible wavelengths.", "doi": "10.1086/175956", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1995-07-20", "series_number": "1", "volume": "448", "issue": "1", "pages": "240-263" }, { "id": "authors:dxfmh-q1z15", "collection": "authors", "collection_id": "dxfmh-q1z15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150114-072940385", "type": "article", "title": "The performance and calibration of WFPC2 on the Hubble Space Telescope", "author": [ { "family_name": "Holtzman", "given_name": "Jon", "clpid": "Holtzman-J-A" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R-E" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Matthews", "given_name": "Lynn D.", "clpid": "Matthews-L-D" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The WFPC2 was installed in the Hubble Space Telescope (HST) in 1993 December. Since\nthen, the instrument has been providing high-quality images. A significant amount of calibration data has\nbeen collected to aid in the understanding of the on-orbit performance of the instrument. Generally, the\nbehavior of the camera is similar to its performance during the system-level thermal vacuum test at JPL in\n1993 May. Surprises were a significant charge-transfer-efficiency (CTE) problem and a significant growth\nrate in hot pixels at the original operating temperature of the CCDs (-76 \u00b0C). The operating temperature of\nthe WFPC2 CCDs was changed to -88 \u00b0C on 1994 April 23, and significant improvements in CTE and hot\npixels are seen at this temperature. In this paper we describe the on-orbit performance of the WFPC2. We\ndiscuss the optical and thermal history, the instrument throughput and stability, the PSF, the effects of\nundersampling on photometry, the properties of cosmic rays observed on-orbit, and the geometric distortion\nin the camera. We present the best techniques for the reduction of WFPC2 data, and describe the\nconstruction of calibration products including superbiases, superdarks, and fiat fields.", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1995-02", "series_number": "708", "volume": "107", "issue": "708", "pages": "156-178" }, { "id": "authors:mt8fy-ap215", "collection": "authors", "collection_id": "mt8fy-ap215", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-141413880", "type": "article", "title": "Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2", "author": [ { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have imaged the globular cluster NGC 6681 in the far-UV and visible with WFPC2 on the HST. Our far-UV images show a sparsely populated and fully resolved central region, and we detect 122 stars. The far-UV to visible color-magnitude diagram shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We find one hot horizontal-branch star significantly below the model zero-age horizontal branch, but the rest are consistent with evolutionary models within uncertainties in calibration, distance, and reddening. The center of the cluster harbors two luminous blue stragglers. Our far-UV images graphically confirm that there is no steep density gradient at small radii among the horizontal-branch stars of\nthis post-core-collapse cluster and show no evidence for significant color gradients.", "doi": "10.1086/187593", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1994-11-01", "series_number": "1", "volume": "435", "issue": "1", "pages": "L55-L58" }, { "id": "authors:dg6v0-80592", "collection": "authors", "collection_id": "dg6v0-80592", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-143227780", "type": "article", "title": "First Hubble Space Telescope observations of the brightest stars in the Virgo galaxy M100 = NGC 4321", "author": [ { "family_name": "Freedman", "given_name": "Wendy L.", "orcid": "0000-0003-3431-9135", "clpid": "Freedman-W-L" }, { "family_name": "Hill", "given_name": "Robert", "clpid": "Hill-R" }, { "family_name": "Madore", "given_name": "Barry F.", "orcid": "0000-0002-1576-1676", "clpid": "Madore-B-F" }, { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Westphal", "given_name": "Jim", "clpid": "Westphal-J-A" } ], "abstract": "As part of both the Early Release Observations from the Hubble Space Telescope and the Key Project on the Extragalactic Distance Scale, we have obtained multiwavelength BVR WFPC2 images for the face-on Virgo cluster spiral galaxy M100 = NGC 4321. We report here preliminary results from those observations, in the form of a color-magnitude diagram for -11,500 stars down to V ~ 27 mag and a luminosity function for the brightest blue stars which is found to have a slope of 0.7, in excellent agreement with previous results obtained for significantly nearer galaxies. With the increased resolution now available using WFPC2, the number of galaxies in which we can directly measure Population I stars and thereby quantify the recent evolution, as well as test stellar evolution theory, has dramatically increased by at least a factor of 100. Finally, we find that stars are present in M100 at the colors and luminosities expected for the brightest Cepheid variables in galaxies.", "doi": "10.1086/187587", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1994-11-01", "series_number": "1", "volume": "435", "issue": "1", "pages": "L31-L34" }, { "id": "authors:f3z8h-b3r84", "collection": "authors", "collection_id": "f3z8h-b3r84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-145936133", "type": "article", "title": "The on-orbit performance of WFPC2", "author": [ { "family_name": "Trauger", "given_name": "John T.", "clpid": "Trauger-J-T" }, { "family_name": "Ballester", "given_name": "Gilda E.", "clpid": "Ballester-G-E" }, { "family_name": "Burrows", "given_name": "Christopher J.", "clpid": "Burrows-C-J" }, { "family_name": "Casertano", "given_name": "Stefano", "clpid": "Casertano-S" }, { "family_name": "Clarke", "given_name": "John T.", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "David", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Evans", "given_name": "Robin W.", "clpid": "Evans-R-W" }, { "family_name": "Gallagher", "given_name": "John S., III", "orcid": "0000-0001-8608-0408", "clpid": "Gallagher-J-S-III" }, { "family_name": "Griffiths", "given_name": "Richard E.", "clpid": "Griffiths-R" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Krist", "given_name": "John E.", "clpid": "Krist-J-E" }, { "family_name": "Scowen", "given_name": "Paul A.", "clpid": "Scowen-P-A" }, { "family_name": "Stapelfeldt", "given_name": "Karl R.", "orcid": "0000-0002-2805-7338", "clpid": "Stapelfeldt-K-R" }, { "family_name": "Watson", "given_name": "Alan M.", "clpid": "Watson-A-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The second Wide Field and Planetary Camera (WFPC2) was successfully installed in the Hubble Space\nTelescope during the STS-61 servicing mission in 1993 December. The primary objective of this new camera is\nto provide diffraction-limited photometric imaging over a wide field and a spectral range from 0.12 to l.0 \u00b5m.\nHere we provide an overview of the characteristics of the new instrument and offer our perspectives based on the first 6 months of operations on-orbit.", "doi": "10.1086/187580", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1994-11-01", "series_number": "1", "volume": "435", "issue": "1", "pages": "L3-L6" }, { "id": "authors:tcc8j-w3306", "collection": "authors", "collection_id": "tcc8j-w3306", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150113-150836297", "type": "article", "title": "Wide field camera observations of Baade's Window", "author": [ { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Light", "given_name": "R. M.", "clpid": "Light-R-M" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Worthey", "given_name": "Guy", "clpid": "Worthey-G" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Hunter", "given_name": "Deidre A.", "orcid": "0000-0002-3322-9798", "clpid": "Hunter-D-A" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Kreidl", "given_name": "Tobias J.", "clpid": "Kreidl-T-J" }, { "family_name": "Groth", "given_name": "E. J.", "clpid": "Groth-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have observed a field in Baade's Window using the Wide Field Camera of the Hubble Space Telescope (HST) and obtain V- and /-band photometry down to V~22.5. These data go several magnitudes fainter than previously obtained from the ground. The location of the break in the luminosity function suggests that there are a significant number of intermediate age ( < 10 Gyr) stars in the Galactic bulge. This conclusion rests on the assumptions that the extinction towards our field is similar to that seen in other parts of Baade's Window, that the distance to the bulge is approximately 8 kpc, and that we can determine fairly accurate zero points for the HST photometry. Changes in any one of these assumptions could increase the inferred age, but a conspiracy oflower reddening, a shorter\ndistance to the bulge, and/or photometric zero-point errors would be needed to imply a population entirely older than 10 Gyr. We infer an initial mass function slope for the main-sequence stars, and find that it is consistent with that measured in the solar neighborhood; unfortunately, the slope is poorly constrained because we sample only a narrow range of stellar mass and because of uncertainties in the\nobserved luminosity function at the faint end.", "doi": "10.1086/116768", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1993-11", "series_number": "5", "volume": "106", "issue": "5", "pages": "1826-1838" }, { "id": "authors:52kfy-6q192", "collection": "authors", "collection_id": "52kfy-6q192", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150109-110147033", "type": "article", "title": "The Drift of Saturn's North Polar Spot Observed by the Hubble Space Telescope", "author": [ { "family_name": "Caldwell", "given_name": "John", "clpid": "Caldwell-J" }, { "family_name": "Hua", "given_name": "Xin-Min", "clpid": "Hua-X-M" }, { "family_name": "Turgeon", "given_name": "Benoit", "clpid": "Turgeon-B" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Barnet", "given_name": "Christopher D.", "clpid": "Barnet-C-D" } ], "abstract": "Polar projections of 50 images of Saturn at 889 nanometers and 25 images at 718 nanometers taken by the Hubble Space Telescope in November 1990, as well as 3 images at each wavelength taken in June 1991, have been examined. Among them, 31 show the north polar spot, which is associated with Saturn's polar hexagon, in locations suitable for measurement. In each image, planetocentric coordinates of the polar spot were determined, and the movement of the spot with respect to Saturn's system III rotation rate was studied. During the period of observation, the polar spot had first a short-term westward movement and then a long-term eastward drift. The rate of the long-term drift was \u20130.060 \u00b1 0.008 degrees per day with respect to system III, approximately 50 percent greater than previously determined from Voyager. The original 1980 and 1981 Voyager data were combined with the new Hubble images to form an 11-year base line. The eastward drift over the longer period was \u20130.0569 degrees per day. The long-term drift could be due to uncertainty in the standard value of the internal rotation period, which is 810.7939 \u00b1 0.148 degrees per 24-hour day. The short-term movement in November 1990 has a rate that is greater in magnitude but opposite in sign and probably represents a real, transient motion of the spot relative to the internal rotation system.", "doi": "10.1126/science.260.5106.326", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1993-04-16", "series_number": "5106", "volume": "260", "issue": "5106", "pages": "326-329" }, { "id": "authors:dj4b7-jk126", "collection": "authors", "collection_id": "dj4b7-jk126", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121207-144737606", "type": "article", "title": "Hubble Space Telescope Observations of the 1990 Equatorial\n Disturbance on Saturn: Images, Albedos, and Limb Darkening", "author": [ { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Ingersoll", "given_name": "Andrew P.", "orcid": "0000-0002-2035-9198", "clpid": "Ingersoll-A-P" }, { "family_name": "Barnet", "given_name": "Christopher D.", "clpid": "Barne-C-D" }, { "family_name": "De Jong", "given_name": "Eric M.", "clpid": "De-Jong-E-M" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Caldwell", "given_name": "John", "clpid": "Caldwell-J" } ], "abstract": "In September 1990 a major equatorial eruption on Saturn produced a disturbance that spread in longitude until it completely girdled the planet. We report here on 150 images recorded in six passbands with the Wide Field/Planetary Camera (WF/PC) aboard the Hubble Space Telescope (HST) on 17 and 18 November 1990. For comparison, we used HST-WF/PC observations of Saturn obtained in three colors on 26 August 1990 before the onset of the disturbance, and in six colors on 5 and 6 June 1991 when almost no evidence of the disturbance remained. At both of those times, the equatorial belt was \"normal\" in appearance. Four of the passbands (with mean wavelengths of 336, 435, 546, and 716 nm) were selected for photometric analysis, and a patch of the B ring near the central meridian was used for photometric calibration. Using deconvolved images from all three epochs of observation, we measured reflectivities (I/F) of the disk along parallels of latitude as a function of longitudinal distance from the central meridian and also along the central meridian as a function of latitude from 0\u00b0 to 90\u00b0. The longitudinal measurements cover essentially the whole visible disk; they were made at 1\u00b0 intervals of planetographic latitude from 0\u00b0 to 80\u00b0, and the results are expressed in terms of Minnaert coefficients k and Minnaert albedos (I/F)_0. We find that the cloud particles associated with the disturbance must differ in character from those that normally make up the visible cloud deck on Saturn. They were brighter and bluer, they had greater limb darkening, and their limb darkening was spectrally more neutral. The mutual relationship of those properties is such that features which stand out strongly near the meridian fade to invisibility when near the limb.", "doi": "10.1016/0019-1035(92)90112-K", "issn": "0019-1035", "publisher": "Elsevier", "publication": "Icarus", "publication_date": "1992-12", "series_number": "2", "volume": "100", "issue": "2", "pages": "485-498" }, { "id": "authors:y7db5-wjf56", "collection": "authors", "collection_id": "y7db5-wjf56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141204-071240482", "type": "article", "title": "Hubble Space Telescope Planetary Camera images of R136", "author": [ { "family_name": "Campbell", "given_name": "Bel", "clpid": "Campbell-B" }, { "family_name": "Hunter", "given_name": "Deidre A.", "orcid": "0000-0002-3322-9798", "clpid": "Hunter-D-A" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Code", "given_name": "Arthur", "clpid": "Code-A" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The Planetary Camera of the Hubble Space Telescope has been used to obtain broad and narrowband images ofR136, the core of the massive star cluster 30 Doradus in the Large Magellanic Cloud. R136a, the brightest component ofR136, is shown to have at least 12 separate components, including the eight originally identified by speckle interferometry. Three of the 12 components are previously unidentified\nclose companions of the speckle components. The stars within R136a are found to have luminosities and colors of normal evolved (Wolf-Rayet and blue supergiants) and zero-age main-sequence (ZAMS) massive stars. A narrowband He II filter was used to investigate the Wolf-Rayet stellar population. We find that three stars in R136a are of the Wolf-Rayet type; of the two identified from ground-based data, one is now resolved into two components. We present color-magnitude diagrams and a luminosity function of the stars within the larger region (~2 pc) defined as R136. We find that the stars in R136 are similar in color and luminosity to those of cluster members that lie outside that crowded inner region. The lower end of the color-magnitude diagram corresponds to ZAMS spectral type B3. No red supergiants have been detected within R136. The luminosity per unit area in the inner 1\" (0.25 pc) of\nR136 is \u2265 50 times that of the center of Orion for a comparable area and seven times that of the core\nof NGC 3603. The luminosity per unit area of all of R136 is comparable to that of Orion but is sustained over 130 times the area. An F336W surface brightness profile is constructed for R136 based on the stellar photometry. The distribution is found to be consistent with a pure power law with l(r}\u0251 r^y with y=-1.72\u00b10.06 or with a small core with r_c<0.25\", considerably smaller than predicted from ground-based observations. In the latter case p_0 > 5 X 10^4 M_\u2609 pc^(-3). The implied upper limit on the relaxation time for the cluster is much smaller than the age of 3.5 X 10^6 yrs required by the presence of Wolf-Rayet stars. This suggests that relaxation effects have been very important in determining the observed structure of the cluster unless a large population of lower mass stars is also present.", "doi": "10.1086/116355", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1992-11", "series_number": "5", "volume": "104", "issue": "5", "pages": "1721-1742" }, { "id": "authors:71h2p-atv03", "collection": "authors", "collection_id": "71h2p-atv03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141204-065501740", "type": "article", "title": "Planetary camera observations of the central parsec of M32", "author": [ { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Analysis of V band HST Planetary Camera images of the elliptical galaxy M32 shows that its nucleus is extremely dense and remains unresolved at even the HST diffraction limit. A combined approach of image deconvolution and model fitting is used to investigate the starlight distribution into limiting radii of 0\".04 (0.14 pc at 700 kpc). The logarithmic slope of the brightness profile smoothly flattens from y= -1.2 at 3.4 pc to y= -0.5 at 0.34 pc; interior to this radius the profile is equally consistent with a singular \u00b5(r)\u221d r,^(-1/2) cusp or a small nonisothermal core with r_c<0.37 pc. The isophotes maintain\nconstant ellipticity into tlle center, and there is no evidence for a central point source, disk, dust, or\nany other substructures. The cusp model implies central mass densities p_0 > 3 X 10^7 M_\u2609 pc^(-3) at the\nresolution limit and is consistent with a central M_\u2022 = 3 X 10^6 M_\u2609 black hole; the core model implies p_0\u22484 X 10^6 M_\u2609 pc^(-3). From the viewpoint of long-term stability, we argue that a starlight cusp surrounding a central black hole is the more plausible interpretation of the observations. A core at the implied density and size without a black hole has a relaxation time of only ~7 X 10^7 yr and a short stellar oollision timescale implying wholesale stellar merging over the age of the universe. The core would be strongly vulnerable to collapse and concomitant runaway stellar merging. Collapse may lead\nto formation of a massive black hole in any case if it cannot be reversed by formation of a binary from high-mass merger products. Regardless of the ultimate fate of the core, however, structural evolution of the core will always be accompanied by strong evolution of the core population-the constant isophote shape and absence of a central color gradient appear to show that such evolution has not occurred. In contrast, the high velocities around a black hole imply long relaxation and stellar collision\ntimes for the cusp population compared to the age of the universe.", "doi": "10.1086/116254", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1992-08", "series_number": "2", "volume": "104", "issue": "2", "pages": "552-562" }, { "id": "authors:946qh-yev74", "collection": "authors", "collection_id": "946qh-yev74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141126-072722216", "type": "article", "title": "Planetary Camera observations of the M87 stellar cusp", "author": [ { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Lynds", "given_name": "C. Roger", "clpid": "Lynds-C-R" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Analysis of V and I band HST Planetary Camera images of the giant elliptical galaxy M87 show that its central starlight distribution is consistent with the black hole M_\u2022 = 2.6 X 10^9 M_\u2609 cusp model proposed for M87 by Young et al. [ApJ, 221, 721 (1978)]. A combined approach of image deconvolution and modeling is used to investigate the starlight distribution into limiting radii of \u22480\".04 (3 pc at 16 Mpc). The central structure of M87 can be described by three components: a power-law starlight profile\nof the form \u00b5(r)\u221da:r^(-1/4) for r<3\", a central nonthermal point source, and optical counterparts of the jet knots N1 and M identified by VLBI observations. M87 lacks a constant surface brightness core, and its central starlight luminosity density exceeds 10^3L_\u2609 pc^(-3) (I band) for r< 10 pc. The profile strongly resembles a stellar cusp associated with a massive black hole. A review of existing velocity dispersion observations suggests that the Young et al. black hole mass can be accommodated to the observations\nwith minor adjustments of dynamical models. The central luminosity spike itself remains unresolved at HST resolution, with r_c < 1 pc. The spike has optical spectral index \u0251= -0.46 \u00b1 0.20 and is at least as blue if not bluer than the rest of the M87 jet. The total nonthermal flux in the inner 1\" of M87 agrees well with the central radio flux and the radio-optical spectral index of the rest of the jet. It is also consistent with the spectral-line dilution seen by Dressler & Richstone [ApJ, 348, 120 ( 1990)]; we thus argue that the spike is completely nonthermal.", "doi": "10.1086/116095", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1992-03", "series_number": "3", "volume": "103", "issue": "3", "pages": "703-710" }, { "id": "authors:y391h-gk530", "collection": "authors", "collection_id": "y391h-gk530", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141201-073843900", "type": "article", "title": "Planetary Camera observations of NGC 1275 - Discovery of a central population of compact massive blue star clusters", "author": [ { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hunter", "given_name": "Deidre A.", "orcid": "0000-0002-3322-9798", "clpid": "Hunter-D-A" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "C. Roger", "clpid": "Lynds-C-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have discovered a population of bright blue pointlike sources within 5 kpc of the nucleus of NGC 1275 using HST Planetary Camera observations. The typical object has M_v~- 12 to - 14 (H_0 = 75 km s^(-1) Mpc^(-1); the brightest has M_v~-16. They are all blue, with V- R\u227e0.3. The color distribution and lack of excess Ha emission are consistent with nearly all being continuum sources. Many of the sources are unresolved even with the HST and consequently have sizes of \u227e 15 pc. We suggest that these are young star clusters that will evolve to look like globular clusters. They are bluer than any clusters seen in the Milky Way or M87, and brighter than the blue clusters seen in the LMC. We derive ages of several hundred million years or less and corresponding masses of 10^5-10^8 M_\u2609. The existence of these young clusters may be connected with a current or previous interaction with another galaxy, with the cooling flow in NGC 1275, or with some combination. Structure is detected in the underlying galaxy light that is suggestive of a merge between NGC 1275 and a second galaxy some 10^8 yr ago. If this merger triggered star formation, it would naturally account for the observed uniformity of cluster\ncolors. Steady-state star formation in the x-ray cooling flow would imply a wider range in cluster age and color than is seen, unless the clusters disrupt. An interaction with the projected high-velocity, infalling system cannot explain the observations because this system has not yet reached the center of NGC 1275 where the clusters are concentrated, and because it has a total interaction time that is far too short for either the observed cluster lifetimes or the dynamical lifetime of structure in the galaxy. If the presence of recently formed protoglobulars around NGC 1275 is related to a previous merger, this\nwould remove an important objection to the merger hypothesis for elliptical galaxy origins, provided\nthat adequate gas is available in the merger for their formation.", "doi": "10.1086/116094", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1992-03", "series_number": "3", "volume": "103", "issue": "3", "pages": "1020-1023" }, { "id": "authors:yffc2-m1y39", "collection": "authors", "collection_id": "yffc2-m1y39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150213-095346940", "type": "book_section", "title": "Science with the Second Wide Field and Planetary Camera", "book_title": "Science with the Hubble Space Telescope", "author": [ { "family_name": "Trauger", "given_name": "John", "clpid": "Trauger-J-T" }, { "family_name": "Burrows", "given_name": "Chris", "clpid": "Burrows-C-J" }, { "family_name": "Clarke", "given_name": "John", "clpid": "Clarke-J-T" }, { "family_name": "Crisp", "given_name": "Dave", "orcid": "0000-0002-4573-9998", "clpid": "Crisp-D" }, { "family_name": "Gallagher", "given_name": "Jay", "clpid": "Gallagher-J-S" }, { "family_name": "Griffiths", "given_name": "Richard", "clpid": "Griffiths-R-E" }, { "family_name": "Hester", "given_name": "Jeff", "clpid": "Hester-J-J" }, { "family_name": "Hoessel", "given_name": "John", "clpid": "Hoessel-J-G" }, { "family_name": "Holtzman", "given_name": "Jon", "clpid": "Holtzman-J-A" }, { "family_name": "Mould", "given_name": "Jeremy", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Westphal", "given_name": "Jim", "clpid": "Westphal-J-A" } ], "contributor": [ { "family_name": "Benvenuti", "given_name": "Piero", "clpid": "Benvenuti-P" }, { "family_name": "Schreier", "given_name": "Ethan J.", "clpid": "Schreier-E-J" } ], "abstract": "With the commencement of Cycle 4 observations, the General Observer community will have access to the second Wide Field and Planetary Camera (WFPC-2), a replacement for the original WFPC instrument. WFPC-2, a wide-field photometric camera which covers the spectrum from 1200 to 10000 Angstroms, will be installed in the Hubble radial bay during the currently manifested December 1992 Shuttle servicing mission. Besides optical correction for the aberrated Hubble primary mirror, the WFPC-2 incorporates\nevolutionary improvements in photometric imaging capabilities. The CCD sensors, signal chain electronics,\nfilter set, FUV performance, internal calibrations, and operational efficiency have all been improved through\nnew technologies and lessons learned from WFPC operations and Hubble experience since launch. Here we provide an overview of the new instrument, beginning with the assumption that the reader is already familiar with the original WFPC now in service.", "isbn": "9783923524471", "publisher": "Garching bei M\u00fcnchen", "place_of_publication": "Sardinia, Italy", "publication_date": "1992", "pages": "509-516" }, { "id": "authors:5a58g-dz567", "collection": "authors", "collection_id": "5a58g-dz567", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-103552498", "type": "article", "title": "Hubble Space Telescope imaging of \u03b7 Carinae", "author": [ { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" } ], "abstract": "We present new high spatial resolution observations of the material around \u03b7 Carinae obtained with the Hubble Space Telescope Wide Field/Planetary Camera. The star \u03b7 Carinae is one of the most massive and luminous stars in our Galaxy, and has been episodically expelling significant quantities of gas over the last few centuries. The morphology of the bright central nebulosity (the homunculus) indicates that it is a thin shell with very well defined edges, and is clumpy on 0\".2 (~10^(16)cm) scales. An extension to the northeast of the star {NN/NS using Walborn's [ApJL, 204, L17 ( 1976)] nomenclature} appears to be a stellar jet and its associated bow shock. The bow shock is notable for an intriguing series of parallel linear features across its face. The S ridge and the W arc appear to be part of a \"cap\" of emission located\nto the SW and behind the star. Together, the NE jet and the SW cap suggest that the symmetry axis for the system runs NE-SW rather than SE-NW, as previously supposed. Overall, the data indicate that the material around the star may represent an oblate shell with polar blowouts, rather than a bipolar flow.", "doi": "10.1086/115898", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1991-08", "series_number": "2", "volume": "102", "issue": "2", "pages": "654-657" }, { "id": "authors:gpkzq-tya78", "collection": "authors", "collection_id": "gpkzq-tya78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141126-105710198", "type": "book_section", "title": "Reduction of PG:1115+080 Images", "author": [ { "family_name": "Groth", "given_name": "E. J.", "clpid": "Groth-E-J" }, { "family_name": "Kristian", "given_name": "Jerome A.", "clpid": "Kristian-J-A" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Campbell", "given_name": "Bel", "clpid": "Campbell-B" }, { "family_name": "Code", "given_name": "Arthur", "clpid": "Code-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Hoessel", "given_name": "John G.", "clpid": "Hoessel-J-G" }, { "family_name": "Hunter", "given_name": "Deidre", "clpid": "Hunter-D" }, { "family_name": "Kelsall", "given_name": "T.", "clpid": "Kelsall-T" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "Mackie", "given_name": "Glen", "clpid": "Mackie-G" }, { "family_name": "Monet", "given_name": "David G.", "clpid": "Monet-D-G" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Seidelmann", "given_name": "P. Kenneth", "clpid": "Seidelmann-P-K" }, { "family_name": "Smith", "given_name": "Brad", "clpid": "Smith-Brad" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "contributor": [ { "family_name": "Kinney", "given_name": "A. L.", "clpid": "Kinney-A-L" }, { "family_name": "Blades", "given_name": "J. C.", "clpid": "Blades-J-C" } ], "abstract": "The data are three exposures in PC6 through F785LP obtained on March 3, 1991. The exposure times are 120, 400, and 400 seconds. The data are reduced with the \"standard\" WFPC reduction scheme: A-to-D correction, DC bias subtraction, AC bias subtraction, dark current subtraction, preflash subtraction, and flat field normalization, using the best available calibration data. The exposures are combined into a weighted average normalized to 400 seconds exposure time, so one DN (data number) is about 17.25 electrons. At this step, cosmic rays are removed by intercomparison of the three images.", "publisher": "Baltimore, Md. Space Telescope Science Institute", "publication_date": "1991-05" }, { "id": "authors:nf4h5-pnn53", "collection": "authors", "collection_id": "nf4h5-pnn53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-143941746", "type": "article", "title": "The Postcollapse core of M15 imaged with the HST planetary camera", "author": [ { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Kelsall", "given_name": "T.", "clpid": "Kelsall-T" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "C. Roger", "clpid": "Lynds-C-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have obtained U-band images of the M15 core with the Planetary Camera of the Hubble Space Telescope. We are able to resolve stars down to the main-sequence turnoff (m_v\u2248 19.4) into the cluster center. We use crowded field photometry techniques to decompose M15 into bright resolved stars and a residual component consisting of stars at turnoff brightness or fainter. The residual component comprises 59% of the cluster light and follows a y = -0.71 power-law distribution for r > 1\". The residual component flattens off interior to this radius and has a large core with r_c = 2\".2 = 0.13 pc. The core size may reflect postcollapse core expansion. The resolved stars have a slightly shallower distribution (y = - 0.53) but have an abrupt overdensity for r < 1\".5, which accounts for the unresolved surface brightness cusp at ground resolution. The bright stars do not become more highly concentrated at still smaller radii, however; neither the bright stars nor the residual component form a cusp at subarcsecond resolution. The total central density of light in all components is 8 x 10^5 L_\u2609 pc^(-3) (U-band). The Peterson, Seitzer, and Cudworth central velocity dispersion implies\na high core M/L \u2248 8 (U-band). The existence of a core rather than a cusp at the 0.1 pc scale may imply that\nthe centrally deduced dark matter is in a diffuse form rather than a massive black hole.", "doi": "10.1086/185955", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L45-L49" }, { "id": "authors:12y0n-k5017", "collection": "authors", "collection_id": "12y0n-k5017", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-142401412", "type": "article", "title": "The core of the nearby S0 galaxy NGC 7457 imaged with the HST planetary camera", "author": [ { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Kelsall", "given_name": "T.", "clpid": "Kelsall-T" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "C. Roger", "clpid": "Lynds-C-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have observed the nearby S0 galaxy NGC 7457 with the Planetary Camera of the Hubble Space Telescope. Spatial structure is observable at the diffraction-limited resolution of the 2.4 m HST primary despite the effects of spherical aberration. The central distribution of starlight appears consistent with a y ~ -1.0 power law for r < 600 pc, plus a possible additional stellar nucleus with L - 1 x 10^7 L_\u2609 (V band). We find no evidence of a core to limits r_c <0\".052 = 3.4 pc (H_0 = 80 km s^(-1) Mpc^(-1)), in contrast to a priori estimates of r_c ~ 30 pc based on total galaxy luminosity. The center of NGC 7457 remains unresolved at HST resolution and has a central luminosity density p_0 > 3 x 10^4 L_\u2609 pc^(-3) (V band). This is now the second densest core known after M32. From the ground, NGC 7457 resembles any number of unresolved elliptical galaxies, which suggests that compact dense cores may be common. The images of NGC 7457 demonstrate that HST can still provide unique and astrophysically interesting information on the central structure of galaxies.", "doi": "10.1086/185954", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L41-L44" }, { "id": "authors:f892y-q0138", "collection": "authors", "collection_id": "f892y-q0138", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-135146838", "type": "article", "title": "Stellar photometry with the Hubble Space Telescope Wide-field/Planetary camera - A progress report", "author": [ { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Hunter", "given_name": "Deidre", "clpid": "Hunter-D" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Campbell", "given_name": "Bel", "clpid": "Campbell-B" }, { "family_name": "Code", "given_name": "Arthur", "clpid": "Code-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Kelsall", "given_name": "T.", "clpid": "Kelsall-T" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Seidelmann", "given_name": "P. Kenneth", "clpid": "Seidelmann-P-K" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We describe the prospects for the use of the Wide-Field/Planetary Camera (WFPC) for stellar photometry.\nThe large halos of the point-spread function (PSF) resulting from spherical aberration and from spatial, temporal, and color variations of the PSF are the main limitations to accurate photometry. Degradations caused\nby crowding are exacerbated by the halos of the PSF. Here we attempt to quantify these effects and determine the current accuracy of stellar photometry with the WFPC. In realistic cases, the brighter stars in crowded fields have 0.09 mag errors; fainter stars have larger errors depending on the degree of crowding. We find that measuring Cepheids in Virgo Cluster galaxies is not currently possible without inordinate increases in exposure times.", "doi": "10.1086/185953", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L35-L40" }, { "id": "authors:hmx5a-5pa37", "collection": "authors", "collection_id": "hmx5a-5pa37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141126-091355675", "type": "article", "title": "Hubble Space Telescope Wide-Field/Planetary Camera images of Saturn", "author": [ { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Seidelmann", "given_name": "P. Kenneth", "clpid": "Seidelmann-P-K" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Smith", "given_name": "Bradford A.", "clpid": "Smith-B-A" } ], "abstract": "Saturn was recorded in blue, green, and \"red\" light with the Wide-Field/Planetary Camera aboard the Hubble Space Telescope. Owing to relatively high signal levels over most of the planet's image, a dramatic Improvement in the visibility of image detail was achieved by deconvolving the raw images, which had suffered severely from the spherical aberration of the HST optics. The deconvolved images are superior in quality to anything now achievable with ground-based telescopes. On Saturn, the polar hexagon seen by the Voyager spacecraft is still there, but some of the structure of the belts and zones has changed. The B-ring\nspokes were not visible.", "doi": "10.1086/185956", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L51-L53" }, { "id": "authors:jf1m7-83d33", "collection": "authors", "collection_id": "jf1m7-83d33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-132834532", "type": "article", "title": "NGC 1068 - Resolution of nuclear structure in the optical continuum", "author": [ { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Baum", "given_name": "William A.", "clpid": "Baum-W-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Kristian", "given_name": "Jerome A.", "clpid": "Kristian-J-A" }, { "family_name": "Seidelmann", "given_name": "P. Kenneth", "clpid": "Seidelmann-P-K" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "An optical continuum image of the Seyfert galaxy NGC 1068 has been obtained with the Planetary Camera on the Hubble Space Telescope as part of the SAO/ERO program. The filter used, F547M, has an effective wavelength and a width of approximately 5470 and 650 A and excludes all discrete emission lines that might be present. The point-spread function, although compromised by the aberrations of the telescope optics, does permit significant response at the 0\".1 resolution originally anticipated. Deconvolution of the image for the effects of the point-spread function reveals a bright nucleus embedded in an irregular cloudlike structure which is well differentiated against the background of the galaxy. The nucleus is resolved, with a FWHM of ~0\".15, or 11 pc and there is no evidence for any unresolved nuclear component. The lack of an unresolved point source is consistent with the picture in which the broad-line region is seen indirectly via electron scattering, but the precise geometry of the scattering region cannot yet be inferred. The cloud surrounding the nucleus is elongated in the NE-SW direction and has extreme dimensions of 3\".5 x 1\".7 (255 x 124 pc). Although the extent of the cloud is roughly centered on the nucleus, its brightness centroid is situated 0\".4 southwest of the nucleus. Because of the relative photometric dominance of the cloud with respect to both the nucleus and the underlying galaxy and the corresponding dominance of unpolarized star light found by Antonucci and Miller, the conclusion seems inescapable that the light from the cloud is contributed largely by stars. But in appearance the cloud is distinctly dissimilar to our expectation for either\nyoung or old stellar systems, and it seems to bear no simple relationship to the numerous features that have\nheretofore been resolved at other optical, infrared, and radio wavelengths. A determination of the true nature\nof both the cloud and the nuclear feature through spectroscopic and polarimetric measurements is of the\nhighest priority.", "doi": "10.1086/185952", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L31-L34" }, { "id": "authors:2jwk0-0wm19", "collection": "authors", "collection_id": "2jwk0-0wm19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141126-100020453", "type": "article", "title": "Ionization fronts and shocked flows - The structure of the Orion Nebula at 0\".1", "author": [ { "family_name": "Hester", "given_name": "J. Jeff", "clpid": "Hester-J-J" }, { "family_name": "Gilmozzi", "given_name": "R.", "clpid": "Gilmozzi-R" }, { "family_name": "O'Dell", "given_name": "C. R.", "clpid": "O'Dell-C-R" }, { "family_name": "Faber", "given_name": "S. M.", "orcid": "0000-0003-4996-214X", "clpid": "Faber-S-M" }, { "family_name": "Campbell", "given_name": "Bel", "clpid": "Campbell-B" }, { "family_name": "Code", "given_name": "Arthur", "clpid": "Code-A" }, { "family_name": "Currie", "given_name": "Douglas G.", "clpid": "Currie-D-G" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Ewald", "given_name": "S. P.", "orcid": "0000-0002-1567-9154", "clpid": "Ewald-S-P" }, { "family_name": "Groth", "given_name": "Edward J.", "clpid": "Groth-E-J" }, { "family_name": "Holtzman", "given_name": "Jon A.", "clpid": "Holtzman-J-A" }, { "family_name": "Kelsall", "given_name": "T.", "clpid": "Kelsall-T" }, { "family_name": "Lauer", "given_name": "Tod R.", "clpid": "Lauer-T-R" }, { "family_name": "Light", "given_name": "Robert M.", "clpid": "Light-R-M" }, { "family_name": "Lynds", "given_name": "Roger", "clpid": "Lynds-R" }, { "family_name": "O'Neill", "given_name": "Earl J., Jr.", "clpid": "O'Neill-E-J-Jr" }, { "family_name": "Shaya", "given_name": "Edward J.", "clpid": "Shaya-E-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We present HST Wide-Field Camera images of a field in the Orion Nebula obtained in emission from [S II], H\u03b2, and [O II]. The morphology of the [S II] emission is markedly different from the other lines. While H\u03b2 and [O II] are distributed fairly smoothly, [S II] is dominated by filamentary features with widths between 0\".1 and 1\" which sharply highlight ionization fronts moving into dense neutral material. These photoionization fronts act as probes of the structure of the cavity walls of this blister H II region. Their morphology indicates that while the surfaces into which they are moving are textured, subarcsecond clumps with high density contrast are uncommon. An exception is a bow shock-shaped ionization front seen along the face of a solar system-sized (0\".6 = 270 AU) clump which is itself seen in extinction.\nThe field contains a number of HH objects and related structures, many of which were previously recognized\nas such, but whose complex structure is revealed here by the resolution of HST. These include M42 HH 1, which is seen to be an intricate structure of knots and filaments with a head-tail morphology. M42 HH 2 shows structure from both the shocked cavity walls and the shocked atomic outflow. M42 HH 5-7 break into numerous condensations with an appearance reminiscent of HH 7-11. All objects with a bow shockshaped structure (i.e., M42 HH 1, 5, 7, and 10) show enhanced H\u03b2 emission at the apex of the structure where\nthe shock should be strongest. M42 HH 8 and 9 may be HH objects viewed face-on, or alternatively condensations\nphotoionized by a nearby A or B star. Emission from [S II] traces shocks at the walls of an ionized jet apparently emanating from a star in a dark cloud. This cloud seen in extinction is coincident with H_2 Peak 1, which we propose is on the near side of the nebula.", "doi": "10.1086/185962", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "1991-03-10", "series_number": "2", "volume": "369", "issue": "2", "pages": "L75-L78" }, { "id": "authors:b58ea-ygw30", "collection": "authors", "collection_id": "b58ea-ygw30", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141201-071047917", "type": "book_section", "title": "Inner Coma Imaging of Comet Levy (1990c) with the Hubble Space Telescope", "book_title": "Asteroids, Comets, Meteors 1991", "author": [ { "family_name": "Weaver", "given_name": "H. A.", "orcid": "0000-0003-0951-7762", "clpid": "Weaver-H-A" }, { "family_name": "A'Hearn", "given_name": "M. F.", "clpid": "A'Hearn-M-F" }, { "family_name": "Feldman", "given_name": "P. D.", "clpid": "Feldman-P-D" }, { "family_name": "Arpigny", "given_name": "C.", "clpid": "Arpigny-D" }, { "family_name": "Baum", "given_name": "W. A.", "clpid": "Baum-W-A" }, { "family_name": "Brandt", "given_name": "J. C.", "clpid": "Brandt-J-C" }, { "family_name": "Light", "given_name": "R. M.", "clpid": "Light-R-M" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Observations of comet Levy (1990c) were carried out with the Hubble Space Telescope (HST) on UT 27 Sep 1990. At that time, both the heliocentric and geocentric distances were ~1 AU. The comet was imaged with the Wide Field Camera (WFC) through both red and blue filters, which were selected to isolate continuum emission peaking sharply at the nucleus. Each WFC pixel is 0.\"1 on a side, corresponding to 78 km at the comet. The longest exposures (4 sec) through the red filter had sufficient signal to noise that image deconvolution could be used to recover virtually the full spatial resolution of HST.", "isbn": "0942862074", "publisher": "Lunar and Planetary Institute", "place_of_publication": "Houston, TX", "publication_date": "1991", "pages": "232-232" }, { "id": "authors:qyc1h-0qv62", "collection": "authors", "collection_id": "qyc1h-0qv62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200317-155151693", "type": "book_section", "title": "New advancements in charge-coupled device technology: subelectron noise and 4096 x 4096 pixel CCDs", "book_title": "Charge-Coupled Devices and Solid State Optical Sensors", "author": [ { "family_name": "Janesick", "given_name": "James", "clpid": "Janesick-J-R" }, { "family_name": "Elliott", "given_name": "Tom", "clpid": "Elliott-T-S" }, { "family_name": "Dingiziam", "given_name": "Arsham", "clpid": "Dingiziam-A" }, { "family_name": "Bredthauer", "given_name": "Richard", "clpid": "Bredthauer-R-A" }, { "family_name": "Chandler", "given_name": "Charles", "clpid": "Chandler-C-E" }, { "family_name": "Westphal", "given_name": "James", "clpid": "Westphal-J-A" }, { "family_name": "Gunn", "given_name": "James", "clpid": "Gunn-J-E" } ], "contributor": [ { "family_name": "Blouke", "given_name": "Morley M.", "clpid": "Blouke-M-M" } ], "abstract": "This paper reports on two new advancements in CCD technology. The first area of development has produced a special purpose CCD designed for ultra low-signal level imaging and spectroscopy applications that require sub-electron read noise floors. A nondestructive output circuit operating near its 1/f noise regime is clocked in a special manner to read a single pixel multiple times. Off-chip electronics average the multiple values, reducing the random noise by the square-root of the number of samples taken. Noise floors below 0.5 electrons rms are reported. The second development involves the design and performance of a high resolution imager of 4096 x 4096 pixels, the largest CCD manufactured in terms of pixel count. The device utilizes a 7.5-micron pixel fabricated with three-level poly-silicon to achieve high yield.", "doi": "10.1117/12.19452", "isbn": "9780819402899", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1990-07-01", "pages": "223-237" }, { "id": "authors:54012-1kw21", "collection": "authors", "collection_id": "54012-1kw21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161019-101722396", "type": "book_section", "title": "New advancements in charge-coupled device technology: sub-electron noise and 4096x4096 pixel CCDs", "book_title": "Charge-Coupled Devices and Solid State Optical Sensors", "author": [ { "family_name": "Janesick", "given_name": "James R.", "clpid": "Janesick-J-R" }, { "family_name": "Elliott", "given_name": "Tom S.", "clpid": "Elliott-T-S" }, { "family_name": "Dingiziam", "given_name": "Arsham", "clpid": "Dingiziam-A" }, { "family_name": "Bredthauer", "given_name": "Richard A.", "clpid": "Bredthauer-R-A" }, { "family_name": "Chandler", "given_name": "Charles E.", "clpid": "Chandler-C-E" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" } ], "contributor": [ { "family_name": "Blouke", "given_name": "Morley M.", "clpid": "Blouke-M-M" } ], "abstract": "This paper reports on two new advancements in CCD technology. The first area of development has produced a special purpose CCD designed for ultra low-signal level imaging and spectroscopy applications that require sub-electron read noise floors. A nondestructive output circuit operating near its 1/f noise regime is clocked in a special manner to read a single pixel multiple times. Off-chip electronics average the multiple values, reducing the random noise by the square-root of the number of samples taken. Noise floors below 0.5 electrons rms are reported. The second development involves the design and performance of a high resolution imager of 4096 x 4096 pixels, the largest CCD manufactured in terms of pixel count. The device utilizes a 7.5-micron pixel fabricated with three-level poly-silicon to achieve high yield.", "doi": "10.1117/12.19452", "isbn": "0-8194-0289-3", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1990-07-01", "pages": "223-237" }, { "id": "authors:2fzfm-nq273", "collection": "authors", "collection_id": "2fzfm-nq273", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161019-121958778", "type": "book_section", "title": "Quadrant-CCD star tracker", "book_title": "Charge-Coupled Devices and Solid State Optical Sensors", "author": [ { "family_name": "Clampin", "given_name": "M.", "clpid": "Clampin-M-C" }, { "family_name": "Durrance", "given_name": "S. T.", "clpid": "Durrance-S-T" }, { "family_name": "Barkhouser", "given_name": "R.", "clpid": "Barkhouser-R-H" }, { "family_name": "Golimowski", "given_name": "D. A.", "clpid": "Golimowski-D-A" }, { "family_name": "Wald", "given_name": "A.", "clpid": "Wald-A" }, { "family_name": "Fastie", "given_name": "W. G.", "clpid": "Fastie-W-G" }, { "family_name": "Heidtmann", "given_name": "D. L.", "clpid": "Heidtmann-D-L" }, { "family_name": "Blouke", "given_name": "M. M.", "clpid": "Blouke-M-M" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Janesick", "given_name": "J. R.", "clpid": "Janesick-J-R" }, { "family_name": "Gunn", "given_name": "J. E.", "clpid": "Gunn-J-E" } ], "contributor": [ { "family_name": "Blouke", "given_name": "Morley M.", "clpid": "Blouke-M-M" } ], "abstract": "We discuss the characteristics of a Quadrant-CCD developed by Tektronix for pointing and tracking applications. The device is discussed in the context of its application to the Johns Hopkins University adaptive optics program, where it is being used for the correction of stellar image motion resulting from atmospheric turbulence. The transfer function of the device is discussed and results are presented which demonstrate the Quadrant-CCDs capability to provide offset signals to control a rapid guiding mirror in\nthe Johns Hopkins instrument.", "doi": "10.1117/12.19436", "isbn": "0-8194-0289-3", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1990-07-01", "pages": "217-222" }, { "id": "authors:cbghm-z9888", "collection": "authors", "collection_id": "cbghm-z9888", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180628-144729737", "type": "book_section", "title": "Sub-electron noise charge-coupled devices", "book_title": "Charge-Coupled Devices and Solid State Optical Sensors", "author": [ { "family_name": "Chandler", "given_name": "Charles E.", "clpid": "Chandler-C-E" }, { "family_name": "Bredthauer", "given_name": "Richard A.", "clpid": "Bredthauer-R-A" }, { "family_name": "Janesick", "given_name": "James R.", "clpid": "Janesick-J-R" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" } ], "contributor": [ { "family_name": "Blouke", "given_name": "Morley M.", "clpid": "Blouke-M-M" } ], "abstract": "A charge coupled device designed for celestial spectroscopy has achieved readout noise as low as 0.6 electrons rms. A nondestructive output circuit was operated in a special manner to read a single pixel multiple times. Off-chip electronics averaged the multiple values, reducing the random noise by the square root of the number of readouts. Charge capacity was measured to be 500,000 electrons. The device format is 1600 pixels horizontal by 64 pixels vertical. Pixel size is 28 microns square. Two output circuits are located at opposite ends of the 1600 bit CCD register. The device was thinned and operated backside illuminated at -110 degrees C. Output circuit design, layout, and operation are described. Presented data includes the photon transfer curve, noise histograms, and bar-target images down to 3 electrons signal. The test electronics are described, and future improvements are discussed.", "doi": "10.1117/12.19457", "isbn": "0819402893", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1990-07-01", "pages": "238-251" }, { "id": "authors:2d650-j0t97", "collection": "authors", "collection_id": "2d650-j0t97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-094111675", "type": "book_section", "title": "New advancements in charge-coupled device technology - sub-electron noise and 4096\u00d74096 pixel CCDs", "book_title": "CCDs in Astronomy", "author": [ { "family_name": "Janesick", "given_name": "James", "clpid": "Janesick-J" }, { "family_name": "Elliott", "given_name": "Tom", "clpid": "Elliott-T" }, { "family_name": "Dingizian", "given_name": "Arsham", "clpid": "Dingizian-A" }, { "family_name": "Bredthauer", "given_name": "Richard", "clpid": "Bredthauer-R" }, { "family_name": "Chandler", "given_name": "Charles", "clpid": "Chandler-C" }, { "family_name": "Westphal", "given_name": "James", "clpid": "Westphal-J-A" }, { "family_name": "Gunn", "given_name": "James", "clpid": "Gunn-J-E" } ], "contributor": [ { "family_name": "Jacoby", "given_name": "George H.", "clpid": "Jacoby-G-H" } ], "abstract": "This paper reports on two new advancements in CCD technology. The first area of development has produced a special purpose ceo designed for ultra low-signal level imaging and spectroscopy applications that require sub-electron read noise floors. A nondestructive output circuit operating near its 1/f noise regime is clocked in a\nspecial manner to read a single pixel multiple times.\nOff-chip electronics average the multiple values, reducing the random noise by the square-root of the number of samples taken. Noise floors below 0.5 electrons rms are reported. The second development involves the design and performance of a high resolution imager of 4096x4096 pixels, the largest ceo manufactured in terms of pixel count. The device utilizes a 7.5-micron pixel fabricated\nwith three-level poly silicon to achieve high yield.", "isbn": "0-937707-25-2", "publisher": "Astronomical Society of tje Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "18-39" }, { "id": "authors:syyah-6an77", "collection": "authors", "collection_id": "syyah-6an77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141125-101910826", "type": "book_section", "title": "High speed quadrant CCDs for adaptive optics", "book_title": "CCDs in Astronomy", "author": [ { "family_name": "Clampin", "given_name": "M.", "clpid": "Clampin-Mark-C" }, { "family_name": "Durrance", "given_name": "S. T.", "clpid": "Durrance-S-T" }, { "family_name": "Golimowski", "given_name": "D. A.", "clpid": "Golimowski-David-A" }, { "family_name": "Barkhouser", "given_name": "R,", "clpid": "Barkhouser-R-H" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Heidtmann", "given_name": "D. L.", "clpid": "Heidtmann-D-L" }, { "family_name": "Blouke", "given_name": "M. M.", "clpid": "Blouke-Morley-M" } ], "contributor": [ { "family_name": "Jacoby", "given_name": "George H.", "clpid": "Jacoby-G-H" } ], "abstract": "The Johns Hopkins University is developing an adaptive optics coronagraph for the study of circumstellar material at high resolution. The first generation instrument corrects for image motion, i.e., wavefront tilt, using an image motion sensor coupled to a high speed tip/tilt mirror. The image motion sensor is built around a quadrant CCD which detects offsets from the null position. The performance of this device and present results demonstrating its operation in the laboratory are discussed.", "isbn": "0-937707-25-2", "publisher": "Astronomical Society of the Pacific", "place_of_publication": "San Francisco, CA", "publication_date": "1990", "pages": "367-373" }, { "id": "authors:1pffc-pfq41", "collection": "authors", "collection_id": "1pffc-pfq41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150128-100524971", "type": "article", "title": "Four-shooter: a large format charge-coupled-device camera for the Hale telescope", "author": [ { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" }, { "family_name": "Carr", "given_name": "Michael", "clpid": "Carr-M" }, { "family_name": "Danielson", "given_name": "G. Edward", "clpid": "Danielson-G-E" }, { "family_name": "Lorenz", "given_name": "Ernest O.", "clpid": "Lorenz-E-O" }, { "family_name": "Lucinio", "given_name": "Richard", "clpid": "Lucinio-R" }, { "family_name": "Nenow", "given_name": "Victor E.", "clpid": "Nenow-V-E" }, { "family_name": "Smith", "given_name": "J. Devere", "clpid": "Smith-J-Devere" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Schneider", "given_name": "Donald P.", "clpid": "Schneider-D-P" }, { "family_name": "Zimmermann", "given_name": "Barbara A.", "clpid": "Zimmermann-B-A" } ], "abstract": "We describe an astronomical camera for the 200-in. Hale telescope using four 800 X800 Texas Instruments CCDs in an optical arrangement that allows imaging of a contiguous 1600-pixel-square region of sky. The system employs reimaging optics to yield a scale of 0.33 arcsec per pixel, a good match to the best seeing conditions at Palomar Observatory. Modern high-efficiency coatings are used in the complex optical system to yield a throughput at peak efficiency of nearly 50% (including the losses in the telescope), corresponding to a quantum efficiency on the sky of about 30%. The system uses a fifth CCD in a spectroscopic channel, and it is possible to obtain simultaneous imaging and spectroscopic observations with the system. The camera may also be used in a scanning mode, in which the telescope tracking rate is offset, and the charge is clocked in the chips in such a manner as to keep the charge image aligned with the optical image. In this way, a survey for high-redshift quasars has been carried out over a large area of sky. The instrument has produced images for the most distant clusters of galaxies yet discovered as well as spectra of the most distant galaxies yet observed.", "doi": "10.1117/12.7974149", "issn": "0091-3286", "publisher": "Society of Photo-optical Instrumentation Engineers", "publication": "Optical Engineering", "publication_date": "1987-08-01", "series_number": "8", "volume": "26", "issue": "8", "pages": "779-787" }, { "id": "authors:kb1gq-ngg72", "collection": "authors", "collection_id": "kb1gq-ngg72", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KIRjeb86", "type": "article", "title": "Evidence from Strandings for Geomagnetic Sensitivity in Cetaceans", "author": [ { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" }, { "family_name": "Dizon", "given_name": "Andrew E.", "clpid": "Dizon-A-E" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We tested the hypothesis that cetaceans use weak anomalies in the geomagnetic field as cues for orientation, navigation and/or piloting. Using the positions of 212 stranding events of live animals in the Smith sonian compilation which fall within the boundaries of the USGS East-Coast Aeromagnetic Survey, we found that there are highly significant tendencies for cetaceans to beach themselves near coastal locations with local magnetic minima. Monte-Carlo simulations confirm the significance of these effects. These results suggest that cetaceans have a magnetic sensory systemcomparable to that in other migratory and homing animals, and predict that the magnetic topography and in particular the marine magnetic lineations may play an important role in guiding long-distance migration. The 'map' sense of migratoryanimals may therefore be largely based on a simple strategy of following paths of local magnetic minima and avoiding magnetic gradients.", "issn": "0022-0949", "publisher": "Company of Biologists", "publication": "Journal of Experimental Biology", "publication_date": "1986-01", "volume": "120", "pages": "1-24" }, { "id": "authors:q83p6-p5t60", "collection": "authors", "collection_id": "q83p6-p5t60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150121-101108556", "type": "article", "title": "Eruption Prediction Aided by Electronic Tiltmeter Data at Mount St. Helens", "author": [ { "family_name": "Dzurisin", "given_name": "Daniel", "clpid": "Dzurisin-D" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Johnson", "given_name": "Daniel J.", "clpid": "Johnson-D-J" } ], "abstract": "Telemetry from electronic tiltmeters in the crater at Mount St. Helens contributed to accurate predictions of all six effusive eruptions from June 1981 to August 1982. Tilting of the crater floor began several weeks before each eruption, accelerated sharply for several days, and then abruptly changed direction a few minutes to days before extrusion began. Each episode of uplift was caused by the intrusion of magma into the lava dome from a shallow source, causing the dome to inflate and eventually rupture. Release of magma pressure and increased surface loading by magma added to the dome combined to cause subsidence just prior to extrusion.", "doi": "10.1126/science.221.4618.1381", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1983-09-30", "series_number": "4618", "volume": "221", "issue": "4618", "pages": "1381-1383" }, { "id": "authors:eahp9-0b161", "collection": "authors", "collection_id": "eahp9-0b161", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120712-101416578", "type": "article", "title": "Expendable bubble tiltmeter for geophysical monitoring", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Carr", "given_name": "M. A.", "clpid": "Carr-M-A" }, { "family_name": "Miller", "given_name": "W. F.", "clpid": "Miller-W-F" }, { "family_name": "Dzurisin", "given_name": "Daniel", "clpid": "Dzurisin-D" } ], "abstract": "An unusually rugged highly sensitive and inexpensive bubble tiltmeter has been designed, tested, and built in quantity. These tiltmeters are presently used on two volcanoes and an Alaskan glacier, where they continuously monitor surface tilts of geological interest. This paper discusses the\nmechanical, thermal, and electric details of the meter, and illustrates its performance characteristics in both large ( > 10^(-4) radian) and small ( < 10^(-6) radian) tilt environments. The meter's ultimate sensitivity is better than 2 X 10^(-8) radians rms for short periods (hours), and its useful dynamic range is greater than 10^4. Included is a short description of field use of the instrument for volcano monitoring.", "doi": "10.1063/1.1137408", "issn": "0034-6748", "publisher": "American Institute of Physics", "publication": "Review of Scientific Instruments", "publication_date": "1983-04", "series_number": "4", "volume": "54", "issue": "4", "pages": "415-418" }, { "id": "authors:yqd2t-fr082", "collection": "authors", "collection_id": "yqd2t-fr082", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150127-120301061", "type": "article", "title": "Investigation of the optical fields of flat-spectrum radio sources to faint limiting magnitudes", "author": [ { "family_name": "Peacock", "given_name": "J. A.", "clpid": "Peacock-J-A" }, { "family_name": "Perryman", "given_name": "M. A. C.", "clpid": "Perryman-M-A-C" }, { "family_name": "Longair", "given_name": "M. S.", "clpid": "Longair-M-S" }, { "family_name": "Gunn", "given_name": "J. E.", "clpid": "Gunn-J-E" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "A deep optical survey of the fields of 16 flat-spectrum radio sources has been carried out using the Hale 5-m telescope, with a prototype charge-coupled device as a detector. These sources are members of a complete sample, selected as having S(2.7 GHz) > 1.5 Jy, and were either unidentified, or were identified with very faint objects on the prints of the Palomar Sky Survey.\n\nIdentifications are found for 12 of these objects; six are galaxies and six are stellar objects. Identifications for the 2.7-GHz sample are therefore now 96 per cent complete, allowing much improved redshift distributions to be derived. Values of V/V_(max) for the sample members have also been calculated, with the result that \u3008V/V_(max)\u3009 for the flat-spectrum quasars is 0.68, rather than the values nearer 0.5 derived from studies of deeper samples. This result indicates that both the steep-spectrum and flat-spectrum quasars undergo similar degrees of cosmological evolution.", "doi": "10.1093/mnras/194.3.601", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "1981-07-01", "series_number": "2", "volume": "194", "issue": "2", "pages": "601-612" }, { "id": "authors:8807z-tgp57", "collection": "authors", "collection_id": "8807z-tgp57", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200318-075552996", "type": "book_section", "title": "Care, Feeding, And Use Of Charge-Coupled Device (CCD) Imagers At Palomar Observatory", "book_title": "Solid-State Imagers for Astronomy", "author": [ { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "contributor": [ { "family_name": "Geary", "given_name": "John C.", "clpid": "Geary-J-C" }, { "family_name": "Latham", "given_name": "David W.", "clpid": "Latham-D-W" } ], "abstract": "Both TI and RCA CCDs have been applied to two-dimensional photometry and spectroscopy at Palomar. The optical, mechanical, and electronic properties of these chips are described along with a discussion of drive, processing, and recording techniques. A focal conversion optical system, the \"Prime Focus Universal Extra-galactic Instrument\" (PFUEI) is used to more optimally match the Hale 5 meter plate scale. Calibration and data analysis are discussed with illustrations of results.", "doi": "10.1117/12.965831", "isbn": "9780892523238", "publisher": "Society of Photo-Optical Instrumentation Engineers (SPIE)", "place_of_publication": "Bellingham, WA", "publication_date": "1981-06", "pages": "16-23" }, { "id": "authors:562y4-2yq61", "collection": "authors", "collection_id": "562y4-2yq61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150127-114831118", "type": "article", "title": "Investigations of the optical fields of 3CR radio sources to faint limiting magnitudes - IV", "author": [ { "family_name": "Gunn", "given_name": "J. E.", "clpid": "Gunn-J-E" }, { "family_name": "Hoessel", "given_name": "J. G.", "clpid": "Hoessel-J-G" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Perryman", "given_name": "M. A. C.", "clpid": "Perryman-M-A-C" }, { "family_name": "Longair", "given_name": "M. S.", "clpid": "Longair-M-S" } ], "abstract": "A deep optical survey of the fields of 18 3CR radio sources has been carried out with the Hale 5-m telescope, using a prototype charged coupled device as a detector. These sources were among the few 3CR objects which were either previously unidentified or associated with very faint images\nat the plate limit for which confirmation was required.\nTen new identifications are proposed (3C 65, 3C 68.2, 3C 175.1, 3C 239, 3C 241, 3C 267, 3C 272, 3C 289, 3C 469.1 and 3C 470), and candidates for the remaining eight sources are confirmed (3C 34, 3C 61.1, 3C 184, 3C 220.3, 3C 250, 3C 280, 3C 324, 3C 368). Of these identifications, those for 3C 68.2, 3C 175.1, 3C 250 and 3C 470 are considered provisional, since they are displaced from the radio source axes. In addition, the candidate for the 3C 61.1 is classed as a confirmed identification, although the optical field\nis crowded and an unambiguous identification cannot be made on positional arguments alone. A subsample of 60 sources from the 3CR catalogue, considered by previous workers, is now (provisionally) completely identified. These new results\nare used to construct luminosity distributions at S(l78) \u2265 20 Jy and S(178)\u2265 l0Jy, and the implications of the complete identification rate for models of source evolution formulated by other workers are examined.", "doi": "10.1093/mnras/194.1.111", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "1981-05-15", "series_number": "1", "volume": "194", "issue": "1", "pages": "111-123" }, { "id": "authors:2p1rz-zm246", "collection": "authors", "collection_id": "2p1rz-zm246", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150127-102455939", "type": "article", "title": "Q0957+561: Detailed models of the gravitational lens effect", "author": [ { "family_name": "Young", "given_name": "Peter", "clpid": "Young-P" }, { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Oke", "given_name": "J. B.", "clpid": "Oke-J-B" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Further observations and theoretical work on Q0957+561 are presented. The galaxy responsible for causing multiple gravitational lens images of Q0957+561 has been reobserved spectroscopically, and we give a more accurate redshift z_d =0.36. In 1980 January, component B had brightened by\n0.3 mag and was equal to A. We have further analyzed our CCD data on the surrounding cluster of galaxies, and we give a list of 180 objects (146 galaxies, 32 stars, and 2 QSO images) to a limiting magnitude r=24.5. The data indicate that the center of luminosity of the cluster is about 23\" west of the QSO images. Detailed models of the gravitational lens effect have been computed. These models can explain all optical and radio data for the system. They predict time delays of up to 5 years between variations in the A and B images (with A preceding B). We believe the third image is rather faint and located close to the center of the lens galaxy. It is possible that the third image contributes to the observed galaxy core. We discuss the possibility that this system may be used to measure H_0. Given two time delays among the three images, such measurements may be successful if no further complications in the imaging arise.", "doi": "10.1086/158751", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1981-03-15", "series_number": "3", "volume": "244", "issue": "3", "pages": "736-755" }, { "id": "authors:96z0s-m8k85", "collection": "authors", "collection_id": "96z0s-m8k85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150127-100303494", "type": "article", "title": "The triple quasar Q1115+080A, B, C - A quintuple gravitational lens image", "author": [ { "family_name": "Young", "given_name": "Peter", "clpid": "Young-P" }, { "family_name": "Deverill", "given_name": "Robert S.", "clpid": "Deverill-R-S" }, { "family_name": "Gunn", "given_name": "James E.", "clpid": "Gunn-J-E" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" } ], "abstract": "Spectroscopy and direct imaging of Qll 15+080A,B,C with a CCD camera supports the hypothesis that they are gravitational images of a single object. Spectroscopy of the C III] \u03bb1909 emission line shows all the images to have identical spectra and redshifts (to within 100 km s^(-1)),\nexcept that Bis slightly redder. The position and brightness of the three images has been accurately measured; the images A, B, and Care magnitudes 16.30,18.64, and 18.17, respectively, in the r band, B is 1\". 77 from A in position angle 266\u00b0, and C is 2\".28 away at position angle 322\u00b0. A and C have the same color, but B is redder by 0.23 mag in (g-r). There is no trace of a lens galaxy, which\nmust have a surface brightness of less than 29 mag arcsec^(-2) at a distance of 5\" -8\" from Q1115+080. Three bright galaxies lie near Q1115+080, apparently forming a small group. Gravitational lens imaging by a massive spiral galaxy is explored, and we find a quintuple image model\nresembling Q1115+080 A,B,C. In this model, Q1115+080A is a highly magnified close pair of images oriented in position angle 23\u00b0. An elongation of Q1115+080A at this angle is seen in the CCD pictures.", "doi": "10.1086/158750", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1981-03-15", "series_number": "3", "volume": "244", "issue": "3", "pages": "723-735" }, { "id": "authors:73ps7-1zy65", "collection": "authors", "collection_id": "73ps7-1zy65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120720-104621300", "type": "article", "title": "Coronene and liumogen as VUV sensitive coatings for Si CCD imagers: a comparison", "author": [ { "family_name": "Cowens", "given_name": "M. W.", "clpid": "Cowens-M-W" }, { "family_name": "Blouke", "given_name": "M. M.", "clpid": "Blouke-M-M" }, { "family_name": "Fairchild", "given_name": "T.", "clpid": "Fairchild-T" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Phosphor coatings have long been employed in the detection\nof UV radiation. With the interest in the use of silicon\ncharge coupled device (CCD) imagers as the detector for the\nspace telescope and other space-borne astronomical missions,\na UV sensitive phosphor is desired the emission spectrum of\nwhich usefully matches the spectral response of the CCD.\nSuch a phosphor would provide an unparalleled opportunity\nto image in the UV, the visible, and near IR wavelengths with the same detector. A recent study has suggested that coronene and sodium salicylate (which emit at 500 and 420 nm, respectively) are the most promising candidate phosphors. The potential of a third organic phosphor, liumogen, is the subject of this Letter.", "doi": "10.1364/AO.19.003727", "issn": "0003-6935", "publisher": "Optical Society of America", "publication": "Applied Optics", "publication_date": "1980-11-15", "series_number": "22", "volume": "19", "issue": "22", "pages": "3727-3728" }, { "id": "authors:8nyk8-5cy90", "collection": "authors", "collection_id": "8nyk8-5cy90", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BLOao80", "type": "article", "title": "Ultraviolet downconverting phosphor for use with silicon CCD imagers", "author": [ { "family_name": "Blouke", "given_name": "M. M.", "clpid": "Blouke-M-M" }, { "family_name": "Cowens", "given_name": "M. W.", "clpid": "Cowens-M-W" }, { "family_name": "Hall", "given_name": "J. E.", "clpid": "Hall-J-E" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Christensen", "given_name": "A. B.", "clpid": "Christensen-A-B" } ], "abstract": "The properties and application of a UV downconverting phosphor (coronene) to silicon charge coupled devices are discussed. Measurements of the absorption spectrum have been extended to below 1000 A, and preliminary results indicate the existence of useful response to at least 584 A. The average conversion efficiency of coronene was measured to be ~20% at 2537 A. Imagery at 3650 A using a backside illuminated 800 X 800 CCD coated with coronene is presented.", "issn": "0003-6935", "publisher": "Optical Society of America", "publication": "Applied Optics", "publication_date": "1980-10-01", "series_number": "19", "volume": "19", "issue": "19", "pages": "3318-3321" }, { "id": "authors:dppa8-ssg92", "collection": "authors", "collection_id": "dppa8-ssg92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-132700847", "type": "article", "title": "CCD photometry of the nuclei of three supergiant elliptical galaxies - Evidence for a supermassive object in the center of the radio galaxy NGC 6251", "author": [ { "family_name": "Young", "given_name": "Peter J.", "clpid": "Young-P-J" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have analyzed charged coupled device (CCD) photometry in the g and r bands of three supergiant elliptical galaxies: NGC 4874 and NGC 4889 in the Coma cluster, and the radio\ngalaxy NGC 6251. The profiles of NGC 4874 and NGC 4889 are closely fitted by King models. The profile of NGC 6251 cannot be fitted by a King model, nor by a King model plus a central point luminosity source (the presence of which is suggested by a blue trend in the colors at small radii). The previously studied profile of M87, when convolved with an appropriate Gaussian function to allow for the difference in distance, closely resembles the profile of NGC 6251 (but not those of NGC 4874 or NGC 4889). NGC 6251 was successfully fitted with a luminosity profile containing both a point luminosity source and a central point mass. The value of this point mass cannot be determined without additional dynamical data. However, if the core velocity dispersion is similar to that of other giant ellipticals of the same absolute magnitude, the point\nmass is likely to be about 2.4 x 10^9 M_\u2299, similar to the value reported earlier for M87. The data are also used to derive upper limits for possible central point masses in NGC 4874 and NGC 4889.", "doi": "10.1086/157474", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1979-11-15", "volume": "234", "pages": "76-85" }, { "id": "authors:bef9j-v2c29", "collection": "authors", "collection_id": "bef9j-v2c29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151110-151416100", "type": "article", "title": "Infrared Images of Jupiter at 5-Micrometer Wavelength During the Voyager 1 Encounter", "author": [ { "family_name": "Terrile", "given_name": "Richard J.", "clpid": "Terrile-R-J" }, { "family_name": "Capps", "given_name": "R. W.", "clpid": "Capps-R-W" }, { "family_name": "Backman", "given_name": "D. E.", "clpid": "Backman-D-E" }, { "family_name": "Becklin", "given_name": "E. E.", "clpid": "Becklin-E-E" }, { "family_name": "Cruikshank", "given_name": "D. P.", "clpid": "Cruikshank-D-P" }, { "family_name": "Beichman", "given_name": "C. A.", "orcid": "0000-0002-5627-5471", "clpid": "Beichman-C-A" }, { "family_name": "Brown", "given_name": "R. H.", "clpid": "Brown-R-H" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "A coordinated program to observe Jupiter at high spatial resolution in the 5-micrometer wavelength region was undertaken to support Voyager 1 imaging and infrared radiation experiment targeting. Jupiter was observed over a 5-month period from Palomar and Mauna Kea observatories. The frequency of observations allowed the selection of interesting areas for closer Voyager examination and also provided good short-term monitoring of variations in cloud morphology. Significant global changes in the 5-micrometer distribution are seen over this time period.", "doi": "10.1126/science.204.4396.1007", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1979-06-01", "series_number": "4396", "volume": "204", "issue": "4396", "pages": "1007-1008" }, { "id": "authors:6kx8x-k4817", "collection": "authors", "collection_id": "6kx8x-k4817", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-135159207", "type": "article", "title": "Evidence for a supermassive object in the nucleus of the galaxy M87 from SIT and CCD area photometry", "author": [ { "family_name": "Young", "given_name": "Peter J.", "clpid": "Young-P-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Wilson", "given_name": "Christopher P.", "clpid": "Wilson-C-P" }, { "family_name": "Landauer", "given_name": "Frederick", "clpid": "Landauer-F" } ], "abstract": "Two-dimensional SIT and CCD detectors have been used to measure the surface brightness of the peculiar elliptical radio galaxy M87. Measurements were made in three broad-band colors (B, V, and R) to a distance of 80\" from the nucleus, with 1\" spatial resolution and photometric\naccuracy of the order of 1%. The data are given in some detail and are compared with earlier photographic results. The most obvious feature of the data is a bright, barely resolved central luminosity spike, which is not seen in similar data on other nearby normal ellipticals. Also, attempts to fit isothermal or King models away from the nuclear spike show additional excess luminosity in the central regions of the galaxy (r < 10\"), which cannot be fitted by such a model. A model-independent dynamical analysis, using the photometric data combined with spectrographic results by Sargent et al., shows that the nucleus of M87 contains a compact mass of low luminosity, with M = 5 x 10^9 M_\u2299, r < 100 pc, and M/\u2112 > 60. All of the existing data is well fitted by a King model containing a central black hole of mass M = 3 x 10^9 M_\u2299 and a point\nluminosity source. While such a model is not uniquely required by the data, it is perhaps the most plausible of several possible models considered. At present, M87 is probably the best case for a hypothetical massive black hole in a galaxy nucleus.", "doi": "10.1086/156076", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1978-05-01", "series_number": "1", "volume": "221", "issue": "1", "pages": "721-730" }, { "id": "authors:3tvtj-vey47", "collection": "authors", "collection_id": "3tvtj-vey47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-110202554", "type": "article", "title": "Spectroscopy and photometry of the distant radio galaxy 3C 343.1", "author": [ { "family_name": "Spinrad", "given_name": "Hyron", "clpid": "Spinrad-H" }, { "family_name": "Westphal", "given_name": "James", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" } ], "abstract": "Spectrophotometry of the faint radio galaxy 3C 343.1 shows a strong emission line in the red. If identified with \u22cb3727 of [O II], it yields z = 0.750. The identification is aided by noting that \u22cb3869 of [Ne III] is marginally visible. The optical continuum is relatively blue in color; it is likely to be caused by a population of stars younger than often found in nearby E galaxies. By comparison with other distant galaxies of established z, the isophotal diameter of about 7\" measured for 3C 343.1, is consistent with the proposed redshift and corresponds to a linear size of 70 kpc and to a surface brightness of \u00b5\u03c4 \u2248 26 mag arcsec^(-2).", "doi": "10.1086/182517", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1977-09-15", "volume": "216", "pages": "L87-L89" }, { "id": "authors:kmqzt-he093", "collection": "authors", "collection_id": "kmqzt-he093", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150902-075303635", "type": "article", "title": "Upper Limits for the Visible Counterpart of the Hulse-Taylor Binary Pulsar", "author": [ { "family_name": "Kristian", "given_name": "J.", "clpid": "Kristian-J" }, { "family_name": "Clardy", "given_name": "K. D.", "clpid": "Clardy-K-D" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "The time-averaged intensity of visible pulses from PSR 1913+16 is fainter than V = 23 mag. The absence of visible objects at the pulsar position on the Sky Survey implies a rough limit of M > 3 for the absolute magnitude of the pulsar's binary companion.", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1976-06-15", "series_number": "6", "volume": "206", "issue": "6", "pages": "L143-L144" }, { "id": "authors:scr29-s2937", "collection": "authors", "collection_id": "scr29-s2937", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150709-065058210", "type": "article", "title": "The extension of the Hubble diagram. I. New redshifts and BVR photometry of remote cluster galaxies, and an improved richness correction", "author": [ { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "Absorption-line redshifts for 37 galaxies in 31 remote clusters have been measured with the new sky-subtracting prism spectrograph, using an SIT television detector with digital readout. Twenty-five galaxies in the sample have redshifts larger than z = 0.20. New photoelectric BVR photometry has been obtained for 16 of the clusters. Magnitudes corrected for aperture effect, K-dimming,\ngalactic absorption, cluster richness, and Bautz-Morgan contrast effect are listed. The data permit an improvement in the statistics of the Hubble diagram to z = 0.28 and a new determination of the dependence of the absolute magnitude of the brightest cluster galaxy on cluster richness. A small correlation with richness is found whose amplitude is 0.20 \u00b1 0.18 mag over all Abell richness classes 0-4. As in previous studies, the shallowness of the correlation requires that if M(l) is governed by a general luminosity function, \u03a6(M), for fainter members, then the slope of \u03a6(M) at M(I) must be very steep. The 16 new clusters with photometry have a dispersion in M(l) of 0.26 mag. The dispersion of fully corrected magnitudes for the 65 clusters in the total sample is 0.276 mag. The new points in the Hubble diagram give no indication that the (m, z) relation deviates from the q_0(formal) = + 1 line (i.e. with no evolutionary correction applied), nor that 3C 295 is abnormally bright. The need for more data with z > 0.3 is stressed.", "doi": "10.1086/154324", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1976-05-01", "series_number": "2", "volume": "205", "issue": "2", "pages": "688-695" }, { "id": "authors:hq7r2-qkf71", "collection": "authors", "collection_id": "hq7r2-qkf71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150218-102050266", "type": "article", "title": "Absorption-line redshifts of galaxies in remote clusters obtained with a sky-subtraction spectrograph using an SIT television detector", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" } ], "abstract": "A prism spectrograph with an associated SIT television camera, operating as a two-dimensional detector with\ndigital readout, has been used at the 5-m Hale telescope. The system was tested for its ability to subtract the sky spectrum, and was found to produce difference spectra that are essentially photon noise limited. Redshifts of 14 galaxies in clusters with 0.01 \u2264 z \u2264 0.4 were obtained, each with exposure times of 90 minutes or less. Nine of the redshifts are new. Redshifts for the remaining five agree with previous values to within the measuring errors.\nThe speed and sky-subtraction capabilities of the instrument are sufficient to begin routine measurement of absorption-line redshifts for remote cluster galaxies in an effort to extend the Hubble diagram.", "doi": "10.1086/181786", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1975-05-01", "volume": "197", "pages": "L95-L98" }, { "id": "authors:0ncz0-pad51", "collection": "authors", "collection_id": "0ncz0-pad51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150107-133010454", "type": "article", "title": "Solidified gas samples for shock wave experimentation", "author": [ { "family_name": "Lagus", "given_name": "P. L.", "clpid": "Lagus-P-L" }, { "family_name": "Ahrens", "given_name": "T. J.", "clpid": "Ahrens-T-J" }, { "family_name": "Giles", "given_name": "S. L.", "clpid": "Giles-S-L" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "A cryogenic vacuum system suitable for use with a propellant or light gas gun for performing dynamic compression experiments on solidified gases is described. An optical recording system allows the sample target (suspended in a vacuum of 10^(\u22125) torr) to be monitored until shortly before impact. These experimental techniques have been used to measure Hugoniot data for solid argon and the first Hugoniot data for solid hydrogen.", "doi": "10.1016/0011-2275(75)90110-1", "issn": "0011-2275", "publisher": "Elsevier", "publication": "Cryogenics", "publication_date": "1975-05", "series_number": "5", "volume": "15", "issue": "5", "pages": "246-248" }, { "id": "authors:7fn52-5qx54", "collection": "authors", "collection_id": "7fn52-5qx54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150709-111720711", "type": "article", "title": "Five-micron pictures of Jupiter", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Matthews", "given_name": "Keith", "clpid": "Matthews-K" }, { "family_name": "Terrile", "given_name": "Richard J.", "clpid": "Terrile-R-J" } ], "abstract": "More than 440 five-micron \"video\" pictures of Jupiter with 1\" resolution were made during 1973 September, October,\nand December. Comparisons of these pictures with color photographs show direct, detailed correlations with the darker \"purple\" features. Forty-four of these pictures were made just before Pioneer 10 encounter.", "doi": "10.1086/181447", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1974-03-15", "volume": "188", "pages": "L111-L112" }, { "id": "authors:55vmq-mf206", "collection": "authors", "collection_id": "55vmq-mf206", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-145254741", "type": "article", "title": "Search for a Visible Counterpart of the September 2, 1972 Radio Outburst in Cygnus", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "J.", "clpid": "Kristian-J" }, { "family_name": "Huchra", "given_name": "J. P.", "clpid": "Huchra-J-P" }, { "family_name": "Shectman", "given_name": "S. A.", "clpid": "Shectman-S-A" }, { "family_name": "Brucato", "given_name": "R. J.", "clpid": "Brucato-R-J" } ], "abstract": "Following notification by P. C. Gregory of the discovery of\nthe radio outburst in Cygnus, we attempted to detect a visible\nobject at the radio position over 6 nights, at several wavelengths\nfrom the blue to the near infrared. Direct photographs\nwere taken with the Palomar 48-inch Schmidt camera\nand measurements were made at the prime focus of the 200-inch\ntelescope with a new integrating two-dimensional silicon\nvidicon photometer.", "doi": "10.1038/physci239134a0", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "1972-10-23", "series_number": "95", "volume": "239", "issue": "95", "pages": "134-135" }, { "id": "authors:2afrf-8k984", "collection": "authors", "collection_id": "2afrf-8k984", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-105107972", "type": "article", "title": "On the Optical Search for Centaurus X-3", "author": [ { "family_name": "Brucato", "given_name": "R. J.", "clpid": "Brucato-R-J" }, { "family_name": "Kristian", "given_name": "J.", "clpid": "Kristian-J" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "The optical eclipsing binary LR Cen has been eliminated as a candidate for Cen X-3 on the basis of a real discrepancy of orbital periods. We believe that the position coincidence of Wray 795 with Cen X-3 is not statistically significant.", "doi": "10.1086/181002", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1972-08-01", "volume": "175", "pages": "L137-L139" }, { "id": "authors:4rpdg-jxz98", "collection": "authors", "collection_id": "4rpdg-jxz98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-085830221", "type": "article", "title": "Infrared Diameter of IRC+10216 Determined from Lunar Occultations", "author": [ { "family_name": "Toombs", "given_name": "R. I.", "clpid": "Tooms-R-I" }, { "family_name": "Becklin", "given_name": "E. E.", "clpid": "Becklin-E-E" }, { "family_name": "Frogel", "given_name": "J. A.", "clpid": "Frogel-J-A" }, { "family_name": "Law", "given_name": "S. K.", "clpid": "Law-S-K" }, { "family_name": "Porter", "given_name": "F. C.", "orcid": "0000-0003-1948-8889", "clpid": "Porter-F-C" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Lunar occultations of IRC+10216 have been used to determine the size of the regions emitting 2.2-, 3.5-, 4.8-, and 10-\u03bc radiation. The results are interpreted as the first direct measurement of the physical size of a dust shell surrounding a late-type star.", "doi": "10.1086/180920", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1972-04-15", "series_number": "2", "volume": "173", "issue": "2", "pages": "L71-L74" }, { "id": "authors:ypnre-ms025", "collection": "authors", "collection_id": "ypnre-ms025", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120815-072538993", "type": "article", "title": "Two-Dimensional Silicon Vidicon Astronomical Photometer", "author": [ { "family_name": "McCord", "given_name": "Thomas B.", "clpid": "McCord-T-B" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "We have developed and successfully used an integrating two-dimensional silicon diode array vidicon photometer which is exceptionally well suited for use with telescopes. The video signal is read out from the 1-cm silicon target of the vidicon through a current mode preamplifier and then converted to digital form and stored on magnetic tape. The 256 \u00d7 256 element frames are recorded at 20,000 eight-bit words/sec. The vidicon tube has a published quantum efficiency ranging from 85% at 0.5 \u00b5 to 6% at 1.1 \u00b5 and must be cooled to about -65\u00b0C to eliminate thermal dark current. The minimum detectable signal in the present system is about 1000 carriers per resolution element, limited by preamplifier and other system noise. The system is used as a single-frame camera. The large dynamic range (>10^3), linear response, high quantum efficiency over a large spectral region, and low cost of the system make it well suited for digital direct image and spectroscopy as well as for a laboratory digitizer of two-dimensional material.", "doi": "10.1364/AO.11.000522", "issn": "0003-6935", "publisher": "Optical Society of America", "publication": "Applied Optics", "publication_date": "1972-03-01", "series_number": "3", "volume": "11", "issue": "3", "pages": "522-526" }, { "id": "authors:cb55a-4q715", "collection": "authors", "collection_id": "cb55a-4q715", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-094838015", "type": "article", "title": "1.6\u03bc - 10\u03bc Observations of R Doradus and W Hydrae", "author": [ { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Sargent", "given_name": "W. L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Porter", "given_name": "F. C.", "orcid": "0000-0003-1948-8889", "clpid": "Porter-F-C" } ], "abstract": "Infrared measurements of R Doradus and W Hydrae are presented in order to complement the data of Wing (1971).", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "1971-06", "series_number": "493", "volume": "83", "issue": "493", "pages": "305-306" }, { "id": "authors:xvaca-1zf45", "collection": "authors", "collection_id": "xvaca-1zf45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-092333997", "type": "article", "title": "Interstellar Absorption and Color Excesses in Sco OB-1", "author": [ { "family_name": "Schild", "given_name": "R.", "clpid": "Schild-R" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "New spectral types and photometry are reported for numerous stars in Sco OB-1 and in the foreground of the association. The new data permit reddening in the local spiral arm to be subtracted out in a discussion of reddening in the gas and dust of an adjacent spiral arm. The reddening that occurs within the association Sco OB-1 itself appears to be normal and to have R = 3. Infrared fluxes indicate no deviations (in the reddening law from the ultraviolet to 2.2 \u03bc) from the law for the local spiral arm in Scorpio. The new data show no evidence for a recently reported correlation between absolute magnitude and color excess.", "doi": "10.1086/111110", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "1971-04", "series_number": "3", "volume": "76", "issue": "3", "pages": "237-241" }, { "id": "authors:3vtvb-dj356", "collection": "authors", "collection_id": "3vtvb-dj356", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-091033625", "type": "article", "title": "Optical Polarization and Intensity of the Pulsar in the Crab Nebula", "author": [ { "family_name": "Kristian", "given_name": "J.", "clpid": "Kristian-J" }, { "family_name": "Visvanathan", "given_name": "N.", "clpid": "Visvanathan-N" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Snellen", "given_name": "G. H.", "clpid": "Snellen-G-H" } ], "abstract": "Broad-band photoelectric measurements on nine nights between 1969 February and 1970 February\nshow constant intensity and colors for the pulsar of V = 16.5, B - V = +0.5, U - B = -0.45, and V - R = -0.75, with an accuracy of 10-15 percent in each passband. The ratio of the intensity in the main pulse to that in the subpulse is about 1.8 in each color, with the same accuracy. In the passband \u03bb\u03bb3800-6000, the pulsar intensity repeated within 3 percent on nights 2 months apart. Measurements of linear polarization on four nights in 1969 February, August, and October show repeatable behavior, with the amount of polarization changing smoothly through the pulse from at least 25 percent to near zero and the plane of polarization sweeping through 150\u00b0 during 60\u00b0 of the pulsar's rotation. The time behavior was similar in the main pulse and the subpulse. The discontinuous change of the pulsar's period in 1969 September had no discernible effect upon the intensity, colors, or polarization of the pulses. It is argued that the observed pulses are due to a fixed, polarized emission pattern which is azimuthally scanned as the object rotates, and the sweep of the plane of polarization is interpreted in terms of a very general geometrical model. If the model is valid, then the projection of the rotation axis of the pulsar on the plane of the sky is found directly from the data, with an ambiguity of 90\u00b0, and is either parallel or orthogonal to the integrated magnetic field of the nebula within 20\" of the pulsar. This agreement between the angles of the rotation axis and the magnetic field of the nebula seems too close to be accidental, and implies that the external field, at least in the vicinity of the pulsar, was produced by the pulsar at some stage in its history.", "doi": "10.1086/150680", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1970-11", "volume": "162", "pages": "475-483" }, { "id": "authors:pzmd6-dpt71", "collection": "authors", "collection_id": "pzmd6-dpt71", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-125439424", "type": "article", "title": "Observations of localised 5-micron radiation from Jupiter", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Localized thermal emission from Jupiter has been observed at 5 \u03bc. During April and May 1969 peak\nbrightness temperatures of at least 310\u00b0 K were associated with narrow elongate regions between approximately\n5\u00b0 and 20\u00b0 N. latitude.", "doi": "10.1086/180386", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1969-07", "volume": "157", "pages": "L63-L64" }, { "id": "authors:jmzxc-prk83", "collection": "authors", "collection_id": "jmzxc-prk83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-125439668", "type": "article", "title": "Infrared and Optical Measurements of the Crab Pulsar NP 0532", "author": [ { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Becklin", "given_name": "E. E.", "clpid": "Becklin-E-E" }, { "family_name": "Kristian", "given_name": "J.", "clpid": "Kristian-J" }, { "family_name": "Leighton", "given_name": "R. B.", "clpid": "Leighton-R-B" }, { "family_name": "Snellen", "given_name": "G.", "clpid": "Snellen-G-H" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Observations of the pulsating component of NP 0532 at 2.2 and 1.65 \u03bc are given. The energy density per pulse at 2.2 \u03bc is (3.2 \u00b1 0.4) X 10^(-31) J m^(-2) Hz^(-1) and forms a smooth continuation of the visual data.", "doi": "10.1086/180361", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1969-06", "volume": "156", "pages": "L115-L119" }, { "id": "authors:a8hvt-1bs42", "collection": "authors", "collection_id": "a8hvt-1bs42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-081758829", "type": "article", "title": "Results of Five Nights of Continuous Monitoring of the Optical Flux from SCO X-1", "author": [ { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" } ], "abstract": "Data obtained during five nights of continuous monitoring of the X-ray source Seo X-1 between April and June 1967 are shown in computer-generated point plots.", "doi": "10.1086/150025", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1969-06", "volume": "156", "pages": "927-942" }, { "id": "authors:cwzj2-ftw54", "collection": "authors", "collection_id": "cwzj2-ftw54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-092736430", "type": "article", "title": "Infrared Observations of Eta Carinae to 20 Microns", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" } ], "abstract": "Measurements of \u03b7 Carinae have been obtained at 4.8, 10.1, and 19.5 \u03bc which show a continued increase in flux density into the infrared. The bolometric magnitude is estimated to be -12.", "doi": "10.1086/180346", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1969-04", "volume": "156", "pages": "Art. No. L45" }, { "id": "authors:mm2y2-qgj26", "collection": "authors", "collection_id": "mm2y2-qgj26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-091311244", "type": "article", "title": "On the Nature of Ryle and Bailey's Candidate Star for the Pulsating Radio Source CP 1919", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Snellen", "given_name": "Grant", "clpid": "Snellen-G" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Schmidt", "given_name": "Maarten", "clpid": "Schmidt-Maarten" }, { "family_name": "Oke", "given_name": "J. B.", "clpid": "Oke-J-B" }, { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" }, { "family_name": "Becklin", "given_name": "E. E.", "clpid": "Becklin-E-E" } ], "abstract": "The energy distribution and spectrum of the \"blue\" star near CP 1919 indicate that it is a normal early F, main-sequence star and therefore is not likely to be related to the radio source. No regular variations were found in the light from the star, to within an accuracy of a few tenths of 1 per cent.", "doi": "10.1086/180313", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1969-02", "volume": "155", "pages": "L109-L114" }, { "id": "authors:ge4hp-ax398", "collection": "authors", "collection_id": "ge4hp-ax398", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-081757151", "type": "article", "title": "Rapid Changes in the Optical Intensity and Radial Velocities of the X-Ray Source SCO X-1", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" } ], "abstract": "The optical flux of Seo X-1 was continuously monitored on five separate nights between April and June 1967. Pulse counting was used with sampling intervals of 5 sec on the 100- and 200-inch telescopes and 15 sec on the 60-inch reflector. The error due to photon statistics per sample interval was smaller than 0.007 mag in all cases. The data were processed entirely by computer, using a variety of special digital techniques.\nRapid optical flickering with amplitudes of ~0.02 mag on a time scale of minutes was found on all five nights. These high-frequency fluctuations are superposed on slower continuous variations with amplitudes ~0.15 mag, and on occasional bursts of 0.2 mag which last about 10 min with very short rise and decay times.\nRadial velocities have been measured by a digital method of cross-correlation of microphotometer records of the original photographic plates (Westphal 1966). Velocity changes of about 100 km sec^(-1) were found on two different singly trailed plates, each of 3 hours' duration. The hydrogen lines and He II (\u22cb4686) change in opposite directions, similar to the extar Cyg X-2, suggesting, but not proving, binary motion. Systematic changes of velocity from night to night are set out in Table 2.\nThe distance to Seo X-1 is estimated to be D \u2243 500 pc by three methods, based on the strength of interstellar Ca II K, and on the old nova hypothesis. A firm lower limit of D \u2265 300 pc seems well established.\nThe total X-ray power is \u22432 x 10^(37) h^2 ergs sec^1, where his the distance in units of 500 pc. If the Xray\nenergy is due to bremsstrahlung, this level requires Seo X-1 to continuously pump energy into the hot plasma, replenishing the entire energy store of gas in the cooling time of t_c = 3 X 10^(-15) h^(-1) R^(3/2) sec where R is the radius (in centimeters) of the plasma system. Reasonable values of 10^(11) cm < R < 10^(12) cm give 100 h^(-1) < t_o < 3000 h^(-1) sec, which, remarkably, is the characteristic time of the light flicker.\nMechanical energy due to some type of low-Q oscillation of the system, similar in many respects to that observed in the Sun, seems capable of providing 10^(37) ergs sec^(-1) to the plasma gas. The crucial experiment remains to simultaneously monitor the optical and the X-ray flux over periods of several hours. Detailed correlation of fluctuations is not expected, but the mean X-ray flux might plausibly be expected to vary in periods of fractions of an hour as the mean amplitude of the optical fluctuations changes.", "doi": "10.1086/149746", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1968-10", "volume": "154", "pages": "139-156" }, { "id": "authors:zh5d4-eag54", "collection": "authors", "collection_id": "zh5d4-eag54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-160039028", "type": "article", "title": "Infrared Observations of Eta Carinae", "author": [ { "family_name": "Neugebauer", "given_name": "G.", "clpid": "Neugebauer-G" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Eta Carinae is a non-stellar object less than 5\" in diameter seen projected on a region\nof dense nebulosity. Spectroscopic observations, reviewed by Rodgers and Searle (1967)\nand Aller (1966) have shown strong emission lines superimposed on a smooth continuum.\nThis continuum contributes about 60 per cent of the visual energy and rises\nsteeply into the infrared; no entirely satisfactory mechanism for producing this radiation\nhas been proposed. In this Letter photometric data which extend the continuum observations\nto 1.65, 2.2, and 3.4 \u03bc are presented.", "doi": "10.1086/180185", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1968-05", "volume": "152", "pages": "L89-L94" }, { "id": "authors:dyhx6-q5g94", "collection": "authors", "collection_id": "dyhx6-q5g94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151209-081758574", "type": "article", "title": "Rapid Photometric and Spectroscopic Variations of the X-Ray Source CYG X-2", "author": [ { "family_name": "Kristian", "given_name": "Jerome", "clpid": "Kristian-J" }, { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Fluctuations of 0.04 mag on a time scale of minutes have been found in the optical flux of the candidate star for Cyg X-2. Comparison of radial velocities on a well-widened spectrogram with those of Lynds shows large changes, confirming an earlier suspicion of binary motion by E. M. Burbidge. The systemic velocity is y = -250 km/sec. A lower limit of 300 km/sec for the orbital velocity of one component relative to the other is indicated. The system parameters are m = m_1 + m_2 = 1, P < 0.4 M_\u2609 (days), and \u0251 < 0.01 M_\u2609 a.u., indicative of a very close binary system (m = m_1 + m_2). Eclipses are probable and may have been observed. Spectroscopic evidence may be present for gas streams moving with speeds of greater than 700 km/sec. Three independent arguments are given why the optical flux cannot primarily be non-thermal radiation connected with the production of the X-rays.", "doi": "10.1086/180100", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1967-11", "volume": "150", "pages": "L99-L105" }, { "id": "authors:cy0xd-8gr38", "collection": "authors", "collection_id": "cy0xd-8gr38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-161158355", "type": "article", "title": "Reconnaissance of infrared emission from the lunar nighttime surface", "author": [ { "family_name": "Wildley", "given_name": "Robert L.", "clpid": "Wildley-R-L" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The reconnaissance described in this paper was performed in 1964 and is an extension and refinement of the first observations (1962), in the 8- to 14-\u03bc wavelength region, of the thermal emission from the lunar nighttime surface [Murray and Wildey, 1964]. The present investigation was intended to sample representatively enough of the lunar surface to determine the general character of the lunar nighttime emission and the relative abundance of nighttime infrared anomalies.\n\nMore complete studies of the infrared emission with higher spatial resolution during eclipse were made at about the same time [Saari and Shorthill, 1965].", "doi": "10.1029/JZ072i014p03743", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1967-07-15", "series_number": "14", "volume": "72", "issue": "14", "pages": "3743-3749" }, { "id": "authors:1mmyd-2jp98", "collection": "authors", "collection_id": "1mmyd-2jp98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-155327839", "type": "article", "title": "The Change of Intensity, Color, Line Strength, and Line Position in the QSS 3C 446 during the 1966 Outburst", "author": [ { "family_name": "Sandage", "given_name": "Allan", "clpid": "Sandage-A" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Strittmatter", "given_name": "P. A.", "clpid": "Strittmatter-P-A" } ], "abstract": "During the course of routine observations of quasi-stellar radio sources, 3C 446 was\nfound to be abnormally bright on June 24.4 U.T., 1966 (Sandage 1966). A further observation\non July 12.4 U.T., 1966, confirmed this result, showing that the object had\nundergone an outburst of at least 3.2 mag. sometime between October 5, 1964, and June\n24, 1966. This time interval can be narrowed appreciably because a visual estimate of\nthe V magnitude by Schmidt on September 23 and 25, 1965, gave V not brighter than\n18 on those dates. The event is of particular importance as it enables us to make several\ntests concerning the intensity and position of the emission-line features.", "doi": "10.1086/148893", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1966-10", "volume": "146", "pages": "322-325" }, { "id": "authors:jxk0h-a4r75", "collection": "authors", "collection_id": "jxk0h-a4r75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120920-100048062", "type": "article", "title": "Infrared Observations of Comet 1965f", "author": [ { "family_name": "Becklin", "given_name": "E. E.", "clpid": "Becklin-E-E" }, { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Infrared photometric measurements of Comet 1965f were made on 19 days during October and November, 1965. Absolute intensities as a function of the comet's distance to the Sun were measured in a region centered on the cometary nucleus at wavelengths near 1.65, 2.2, 3.4, and 10 \u00b5. On three days the intensity in the tail was measured.\nColor temperatures were calculated in both the head and tail region from these absolute intensities. From the color temperatures the nature of the emissivity of the emitting particles is derived and the nature of some possible materials is discussed.", "doi": "10.1086/148785", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1966-08", "series_number": "2", "volume": "145", "issue": "2", "pages": "445-453" }, { "id": "authors:t8760-gxr82", "collection": "authors", "collection_id": "t8760-gxr82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-165626398", "type": "article", "title": "The 10-micron limb darkening of Venus", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Observations of 8- to 14-\u00b5 flux from diametric scans of Venus with the 200-inch Hale telescope have been made. The reduced data indicate an unexpected brightening near the Cytherean limb. The data show a more complicated atmospheric structure than postulated by published models. Horizontal inhomogeneity of the emission complicates the interpretation.", "doi": "10.1029/JZ071i011p02693", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1966-06-01", "series_number": "11", "volume": "71", "issue": "11", "pages": "2693-2696" }, { "id": "authors:db23g-9tz93", "collection": "authors", "collection_id": "db23g-9tz93", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-153115941", "type": "article", "title": "Some Astronomical Applications of Cross-Correlation Techniques", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" } ], "abstract": "Cross-correlation techniques have been used for many years to increase the signal-to-noise\nratio of a wide variety of analogue and digital data. A large literature describing\nthese methods exists, and many clever applications have been developed (see Fellgett\n1953, and esp. Woodward 1955, for a basic mathematical development and applications).", "doi": "10.1086/148454", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1965-11", "volume": "142", "pages": "1661-1664" }, { "id": "authors:27aq4-gpn95", "collection": "authors", "collection_id": "27aq4-gpn95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151214-070708469", "type": "article", "title": "Schlieren Technique for Studying Water Flow in Marine Animals", "author": [ { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "A Schlieren optical technique has been developed for studying the flow of water through certain mollusks and brachiopods in sea-water environments. Optical contrast is accomplished by changing either the temperature or salinity of the water. A temperature difference of 0.1\u00b0C or a change in salinity of 0.5 per thousand over a path 1 mm long is visible. The technique may be applied in situ in the ocean or through windows in aquaria.", "doi": "10.1126/science.149.3691.1515-a", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1965-09-24", "series_number": "3691", "volume": "149", "issue": "3691", "pages": "1515-1516" }, { "id": "authors:5g3yb-m2y79", "collection": "authors", "collection_id": "5g3yb-m2y79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141110-104911592", "type": "article", "title": "Thermal infrared emission of the Jovian disk", "author": [ { "family_name": "Wildey", "given_name": "Robert L.", "clpid": "Wildey-R-L" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The 8\u201314 micron infrared emission of Jupiter has been observed on six nights in December 1963 using the 200-inch Hale telescope. The new observations possess twice the resolution of those obtained in 1962. The brightness temperature at the center of the disk appears to be nearly constant at 129\u00b0K. With some slight ambiguity, the light bands are about 0.5\u00b0 cooler in appearance than the dark bands. There is some suggestion of morning-evening asymmetry in one of the bands. The Great Red Spot is found to be from 1.5\u00b0 to 2.0\u00b0 cooler than the surrounding disk at the newer resolution.", "doi": "10.1029/JZ070i015p03711", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1965-08-01", "series_number": "15", "volume": "70", "issue": "15", "pages": "3711-3719" }, { "id": "authors:qf5gq-jcg23", "collection": "authors", "collection_id": "qf5gq-jcg23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-090218795", "type": "article", "title": "The 8-14-\u03bc Appearance of Venus Before the 1964 Conjunction", "author": [ { "family_name": "Westphal", "given_name": "J. A.", "clpid": "Westphal-J-A" }, { "family_name": "Wildey", "given_name": "R. L.", "clpid": "Wildey-R-L" }, { "family_name": "Murray", "given_name": "B. C.", "clpid": "Murray-B-C" } ], "abstract": "In an earlier paper (Murray, Wildey, and Westphal 1963) we have described the detailed\nmapping of the 8-14-\u03bc radiation from Venus using the 200-inch Hale telescope.\nThis paper extends that work over a period of about 7 months from December 15, 1963,\nto June 6, 1964. Detailed maps for 6 days are presented that show the morphology of\nthe upper-atmosphere brightness temperature and illustrate a number of anomalous\nfeatures near the cusps. The problem of atmospheric extinction and the derived brightness\ntemperature is discussed.", "doi": "10.1086/148347", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "1965-08", "volume": "142", "pages": "799-801" }, { "id": "authors:b7626-k8g78", "collection": "authors", "collection_id": "b7626-k8g78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141110-103819651", "type": "article", "title": "In situ acoustic attenuation measurements in glacial ice", "author": [ { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The attenuation coefficient of ice in a temperate valley glacier was measured by spectral analysis of the pressure pulse, directly transmitted through the ice from a small explosion. Values varied from 0.014\u00b1.002/m at 2.5 kc/s to 0.215\u00b1.002/m at 15 kc/s. The attenuation function follows a form \u03b1 = A + B\u0192^4 closely, suggesting Rayleigh-type scattering as the dominant source of attenuation of high-frequency acoustic waves in glacial ice. Scattering from ice crystal boundaries is compatible with the observed scattering coefficient.", "doi": "10.1029/JZ070i008p01849", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1965-04-15", "series_number": "8", "volume": "70", "issue": "8", "pages": "1849-1853" }, { "id": "authors:bt60z-0gd59", "collection": "authors", "collection_id": "bt60z-0gd59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-142925330", "type": "article", "title": "Infrared photometric mapping of Venus through the 8- to 14-micron atmospheric window", "author": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Wildey", "given_name": "Robert L.", "clpid": "Wildey-R-L" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The 200-inch Hale telescope has been used to obtain high-resolution maps, on four mornings juxtaposed about the Mariner 2 encounter, of the brightness temperature of Venus in the 8- to 14-micron wavelength interval. The resolution was about 1/30 of the disk of Venus. The signal-to-noise ratio was in excess of 100. The maps reveal (1) a general limb darkening, (2) a bilateral symmetry about the planet's orbital plane, (3) a very slight wedging of the contours as the only day-to-night effect, and (4) a transient temperature anomaly in the southern hemisphere.", "doi": "10.1029/JZ068i016p04813", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1963-08-15", "series_number": "16", "volume": "68", "issue": "16", "pages": "4813-4818" }, { "id": "authors:pajcd-qqt42", "collection": "authors", "collection_id": "pajcd-qqt42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:WESao63", "type": "article", "title": "An 8-14 micron infrared astronomical photometer", "author": [ { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" }, { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Martz", "given_name": "Dowell E.", "clpid": "Martz-D-E" } ], "abstract": "A system for measurement of 8-14 \u00b5 infrared emission from extra-terrestrial objects is described. The photometric system utilizes a mercury-doped germanium detector cooled to liquid hydrogen temperature to achieve increased sensitivity in this spectral region. A method is presented for minimizing the problem of atmospheric and component emission. The system has been used to measure the radiation from the star \u03b1 Orionis, from the unilluminated moon, and from several planets.", "issn": "0003-6935", "publisher": "Optical Society of America", "publication": "Applied Optics", "publication_date": "1963-07", "series_number": "7", "volume": "2", "issue": "7", "pages": "749-753" }, { "id": "authors:q50da-98q22", "collection": "authors", "collection_id": "q50da-98q22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151211-083052794", "type": "article", "title": "Venus: A Map of Its Brightness Temperature", "author": [ { "family_name": "Murray", "given_name": "Bruce C.", "clpid": "Murray-B-C" }, { "family_name": "Wildey", "given_name": "Robert L.", "clpid": "Wildey-R-L" }, { "family_name": "Westphal", "given_name": "James A.", "clpid": "Westphal-J-A" } ], "abstract": "The 200-inch Hale telescope has been used to make high-resolution maps of the brightness temperature of Venus at wavelengths 8 to 14 microns. Resolution of about 1/30 of the disk reveals a general symmetry about the plane of the orbit, no daynight temperature effects, and a transient temperature anomaly in the southern hemisphere.", "doi": "10.1126/science.140.3565.391", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1963-04-06", "series_number": "3565", "volume": "140", "issue": "3565", "pages": "391-392" } ]