[
{
"id": "authors:n1k0n-8m664",
"collection": "authors",
"collection_id": "n1k0n-8m664",
"cite_using_url": "https://authors.library.caltech.edu/records/n1k0n-8m664",
"type": "article",
"title": "The Surface Mineralogy of the Spinel-rich Asteroids from Mid-infrared Spectroscopy with JWST",
"author": [
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Jacobson",
"given_name": "Seth A.",
"orcid": "0000-0002-4952-9007"
},
{
"family_name": "Wong",
"given_name": "Ian",
"orcid": "0000-0001-9665-8429"
},
{
"family_name": "Tissot",
"given_name": "Fran\u00e7ois L.H.",
"orcid": "0000-0001-6622-2907",
"clpid": "Tissot-F-L-H"
},
{
"family_name": "Martin",
"given_name": "Audrey C.",
"orcid": "0000-0003-3402-1339",
"clpid": "Martin-Audrey-C"
},
{
"family_name": "Lane",
"given_name": "Melissa D.",
"orcid": "0000-0003-3264-3337"
},
{
"family_name": "King",
"given_name": "Oliver R.T.",
"orcid": "0000-0002-6271-0062"
}
],
"abstract": "\n
The “Barbarian” L-type asteroids are purported to contain a high abundance of calcium–aluminum inclusions (CAIs), the oldest solar system solids, based on the dominance of the mineral spinel in their near-infrared spectra. We observed a sample of five objects of this class at 5–28 μm with the Medium-Resolution Spectrometer mode of the Mid-Infrared Instrument on the James Webb Space Telescope. The spectra indicate high-porosity (85%–97% porosity) particulate regolith (<30 μm particles) made up of Mg-rich crystalline olivine (Fo 80–100), with an additional component that could be spinel or amorphous olivine. The spectra of these objects closely resemble that of the oxidized CV3 chondrite Allende. The asteriod spectra additionally exhibit features at 5.75, 6.2, and 7.55 μm that are not definitively identified but may arise from infall of C-bearing materials. These data complement existing visible to near-infrared data of the same targets, which indicate the presence of spinel and minimal hydroxylation, demonstrating the value of multiwavelength spectroscopy to get a more complete picture of the surface compositions of asteroids. The multiwavelength data consistently demonstrate a strong resemblance between the L-type asteroids and CV3 (or possibly CO3) chondrites. The spectra do not require an enhancement in CAI content above that of CV3 chondrites, but the lack of laboratory data prevents a quantitative constraint on CAI content for now. The dominance of crystalline olivine with a high Mg/Fe ratio, and minimal evidence for hydration suggest either an anhydrous formation in the inner solar system, or formation in the outer solar system followed by high-temperature alteration and dehydration.
\n
Our understanding of the formation and evolution of planetary systems has made major advances in the past decade. This progress has been driven in large part by the Atacama Large Millimeter/submillimeter Array (ALMA), which has given us an unprecedented view of solar system bodies themselves, and of the structure and chemistry of forming exoplanetary systems. Within our own solar system, ALMA has enabled the detection of new molecules and isotopologues across moons and comets, as well as placing new constraints on the compositions and histories of small bodies through thermal emission observations. In this article, we highlight some key areas where ALMA has contributed to a deeper understanding of our solar system's formation and evolution, and place these discoveries in the context of our evolving understanding of protoplanetary disks.
",
"doi": "10.1029/2025av001778",
"issn": "2576-604X",
"publisher": "American Geophysical Union",
"publication": "AGU Advances",
"publication_date": "2025-12",
"series_number": "6",
"volume": "6",
"issue": "6",
"pages": "e2025AV001778"
},
{
"id": "authors:2jvv7-zjc89",
"collection": "authors",
"collection_id": "2jvv7-zjc89",
"cite_using_url": "https://authors.library.caltech.edu/records/2jvv7-zjc89",
"type": "monograph",
"title": "The Next-Generation Ground-Based Planetary Radar",
"author": [
{
"family_name": "Lazio",
"given_name": "Joseph",
"clpid": "Lazio-J"
},
{
"family_name": "de Kleer",
"given_name": "Katherine R.",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Ravi",
"given_name": "Vikram",
"orcid": "0000-0002-7252-5485",
"clpid": "Ravi-Vikram"
}
],
"abstract": "Planetary radar observations have a laudable history of “firsts” including determining the astronomical unit with
\nthe precision sufficient for interplanetary navigation, water ice distribution at the Moon’s south pole, water ice
\nindications in the permanently shadowed regions at Mercury’s poles, determining Venus’ rotation state, polar ice
\nand anomalous surface features on Mars, indications that the asteroid (16) Psyche is an exposed metallic core of
\na planetoid, establishing the icy nature of the Jovian satellites, and the initial characterizations of Titan’s surface.
\nIn many cases, these discoveries made by planetary radar systems have motivated missions and mission radar
\ninstruments.
\nThis W. M. Keck Institute of Space Studies study was intended to identify the compelling science and potential
\ntechnical developments required for a next-generation, ground-based planetary radar. As new discoveries have
\noccurred since the first generation of planetary radar observations, our understanding of the Solar System has
\nimproved, and new questions have emerged. One of the study’s motivations was to identify what discoveries might be
\nenabled or how a next-generation planetary radar might address fundamental questions.
\nThe study found that there are three compelling science drivers for a next-generation planetary radar—Venus,
\nnear-Earth asteroids, and the icy moons (“ocean worlds”) of the outer Solar System.
\nFor Venus (“Earth’s evil twin”), long-term measurements of surface geology obtained with a planetary radar
\nwould provide context within which to interpret measurements from a suite of spacecraft planned to explore that
\nplanet over the next decade or more.
\nFor near-Earth asteroids, an improved characterization of the population (or populations) would result from the
\nincrease in both the quantity of near-Earth asteroids that could be tracked and the quality of the data obtained. A
\nplanetary radar would provide precise orbit determinations for planning future spacecraft missions and assessing
\nplanetary defense hazards.
\nFor the outer Solar System, much like for Venus, observations of icy moons/“ocean worlds” over unparalleled
\ndurations could be obtained, even enabling investigations of seasonal changes. Multiple additional science cases
\nwould be enabled, including potentially the tracking of interstellar objects, thereby bridging the fields of Planetary
\nScience and Astrophysics.A second motivation for this study was the two major ground-based planetary radar facilities were approaching
\ntheir half-century anniversaries in 2023, with the Arecibo Observatory planning to celebrate its 60th anniversary of
\noperations and NASA’s Deep Space Network planning to celebrate the 50th anniversary of the start of construction of
\nits Deep Space Station-14 (DSS-14) antenna, which hosts the Goldstone Solar System Radar (GSSR). Notably, and
\nunfortunately, between the two workshops held as part of this study, the Arecibo Observatory collapsed.
\nThis study found that a next-generation, ground-based planetary radar could be implemented as an antenna array,
\nanalogous to those already used in multiple radio astronomy facilities, which would provide greater resilience than a
\nmonolithic antenna.
\nMuch of the technology for such a planetary radar array is maturing. A planetary radar array could be implemented
\nwith solid-state transmitters at each antenna, leveraging considerable commercial investments in solid-state technology
\nand offering the promise of (much) more reliable performance than the traditional vacuum-tube klystrons. Solid-state
\ntransmitters have been prototyped and, in one case, deployed for spacecraft telecommunications.
\nConsiderable promise exists to develop automation and new algorithms, even within existing systems, for both
\nscheduling observations and processing planetary radar data.
\nFollowing this study, two more specific concept studies were conducted: “Cross-Disciplinary Deep Space Radar
\nNeeds Study” and “A Ground-Based Planetary Radar Array”. Both reached similar conclusions: an array of 15-25
\nm diameter antennas equipped with 50-80 kW transmitters would be technically feasible and could address all
\ncompelling science cases identified in this report. A planetary radar array might even be capable of undertaking a
\nsurvey designed to find near-Earth asteroids, a capability not currently available.
",
"doi": "10.26206/2jvv7-zjc89",
"publisher": "W. M. Keck Institute of Space Studies (KISS), California Institute of Technology",
"publication_date": "2025-09-18"
},
{
"id": "authors:r4vd0-cpe10",
"collection": "authors",
"collection_id": "r4vd0-cpe10",
"cite_using_url": "https://authors.library.caltech.edu/records/r4vd0-cpe10",
"type": "article",
"title": "The atmosphere of Titan in late northern summer from JWST and Keck observations",
"author": [
{
"family_name": "Nixon",
"given_name": "Conor A.",
"orcid": "0000-0001-9540-9121"
},
{
"family_name": "B\u00e9zard",
"given_name": "Bruno",
"orcid": "0000-0002-5433-5661"
},
{
"family_name": "Cornet",
"given_name": "Thomas",
"orcid": "0000-0001-5971-0056"
},
{
"family_name": "Coy",
"given_name": "Brandon Park",
"orcid": "0000-0002-0508-857X"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168"
},
{
"family_name": "Es-Sayeh",
"given_name": "Ma\u00ebl",
"orcid": "0000-0002-0643-4323"
},
{
"family_name": "Hammel",
"given_name": "Heidi B.",
"orcid": "0000-0001-8751-3463"
},
{
"family_name": "Lellouch",
"given_name": "Emmanuel",
"orcid": "0000-0001-7168-1577"
},
{
"family_name": "Lombardo",
"given_name": "Nicholas A.",
"orcid": "0000-0001-8621-6520"
},
{
"family_name": "L\u00f3pez-Puertas",
"given_name": "Manuel",
"orcid": "0000-0003-2941-7734"
},
{
"family_name": "Lora",
"given_name": "Juan M.",
"orcid": "0000-0001-9925-1050"
},
{
"family_name": "Rannou",
"given_name": "Pascal",
"orcid": "0000-0003-0836-723X"
},
{
"family_name": "Rodriguez",
"given_name": "S\u00e9bastien",
"orcid": "0000-0003-1219-0641"
},
{
"family_name": "Teanby",
"given_name": "Nicholas A.",
"orcid": "0000-0003-3108-5775"
},
{
"family_name": "Turtle",
"given_name": "Elizabeth P."
},
{
"family_name": "Achterberg",
"given_name": "Richard K."
},
{
"family_name": "Alvarez",
"given_name": "Carlos"
},
{
"family_name": "Davies",
"given_name": "Ashley G."
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Doppmann",
"given_name": "Greg"
},
{
"family_name": "Fletcher",
"given_name": "Leigh N.",
"orcid": "0000-0001-5834-9588"
},
{
"family_name": "Hayes",
"given_name": "Alexander G."
},
{
"family_name": "Holler",
"given_name": "Bryan J.",
"orcid": "0000-0002-6117-0164"
},
{
"family_name": "Irwin",
"given_name": "Patrick G. J.",
"orcid": "0000-0002-6772-384X"
},
{
"family_name": "Jordan",
"given_name": "Carolyn"
},
{
"family_name": "King",
"given_name": "Oliver R. T."
},
{
"family_name": "Kutsop",
"given_name": "Nicholas W."
},
{
"family_name": "Marlin",
"given_name": "Theresa C.",
"orcid": "0009-0003-0670-5474",
"clpid": "Marlin-Theresa-C"
},
{
"family_name": "Melin",
"given_name": "Henrik",
"orcid": "0000-0001-5971-2633"
},
{
"family_name": "Milam",
"given_name": "Stefanie N."
},
{
"family_name": "Molter",
"given_name": "Edward M."
},
{
"family_name": "Moore",
"given_name": "Luke",
"orcid": "0000-0003-4481-9862"
},
{
"family_name": "Nyffenegger-P\u00e9r\u00e9",
"given_name": "Yaniss"
},
{
"family_name": "O'Donoghue",
"given_name": "James",
"orcid": "0000-0002-4218-1191"
},
{
"family_name": "O'Meara",
"given_name": "John"
},
{
"family_name": "Rafkin",
"given_name": "Scot C. R.",
"orcid": "0000-0001-7464-1319"
},
{
"family_name": "Roman",
"given_name": "Michael T.",
"orcid": "0000-0001-8206-2165"
},
{
"family_name": "Rostopchina",
"given_name": "Arina"
},
{
"family_name": "Rowe-Gurney",
"given_name": "Naomi",
"orcid": "0000-0001-8692-5538"
},
{
"family_name": "Schmidt",
"given_name": "Carl"
},
{
"family_name": "Schmidt",
"given_name": "Judy",
"orcid": "0000-0002-2617-5517"
},
{
"family_name": "Sotin",
"given_name": "Christophe",
"orcid": "0000-0003-3947-1072"
},
{
"family_name": "Stallard",
"given_name": "Tom S.",
"orcid": "0000-0003-3990-670X"
},
{
"family_name": "Stansberry",
"given_name": "John A.",
"orcid": "0000-0003-2434-5225"
},
{
"family_name": "West",
"given_name": "Robert A.",
"orcid": "0000-0002-4320-2599"
}
],
"abstract": "Saturn's moon Titan undergoes a long annual cycle of 29.45 Earth years. Titan's northern winter and spring were investigated in detail by the Cassini\u2013Huygens spacecraft (2004\u20132017), but the northern summer season remains sparsely studied. Here we present new observations from the James Webb Space Telescope (JWST) and Keck II telescope made in 2022 and 2023 during Titan's late northern summer. Using JWST's mid-infrared instrument, we spectroscopically detected the methyl radical, the primary product of methane break-up and key to the formation of ethane and heavier molecules. Using the near-infrared spectrograph onboard JWST, we detected several non-local thermodynamic equilibrium CO and CO2 emission bands, which allowed us to measure these species over a wide altitude range. Lastly, using the near-infrared camera onboard JWST and Keck II, we imaged northern hemisphere tropospheric clouds evolving in altitude, which provided new insights and constraints on seasonal convection patterns. These observations pave the way for new observations and modelling of Titan's climate and meteorology as it progresses through the northern fall equinox, when its atmosphere is expected to show notable seasonal changes.",
"doi": "10.1038/s41550-025-02537-3",
"issn": "2397-3366",
"publisher": "Nature Publishing Group",
"publication": "Nature Astronomy",
"publication_date": "2025-07",
"series_number": "7",
"volume": "9",
"issue": "7",
"pages": "969-981"
},
{
"id": "authors:sxztc-9ta60",
"collection": "authors",
"collection_id": "sxztc-9ta60",
"cite_using_url": "https://authors.library.caltech.edu/records/sxztc-9ta60",
"type": "article",
"title": "Observed Latitudinal, Longitudinal and Temporal Variability of Io's Atmosphere Simulated by a Purely Sublimation Driven Atmosphere",
"author": [
{
"family_name": "Dott",
"given_name": "A.\u2010C.",
"orcid": "0009-0002-8605-639X"
},
{
"family_name": "Saur",
"given_name": "J.",
"orcid": "0000-0003-1413-1231"
},
{
"family_name": "Schlegel",
"given_name": "S.",
"orcid": "0000-0002-4779-2813"
},
{
"family_name": "Strobel",
"given_name": "D. F.",
"orcid": "0000-0002-0944-8675"
},
{
"family_name": "de Kleer",
"given_name": "K.",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "de Pater",
"given_name": "I.",
"orcid": "0000-0002-4278-3168"
}
],
"abstract": "How much of Io's SO\u2082 atmosphere is driven by volcanic outgassing or sublimation of surface frost is a question with a considerable history. We develop a time dependent surface temperature model including thermal inertia and the exact celestial geometry to model the radiation driven global structure and temporal evolution of Io's atmosphere. We show that many observations can be explained by assuming a purely sublimation driven atmosphere. We find that a thermal diffusivity ∝ = 2.41 x 10\u207b\u2077 m²s\u207b¹ yields an averaged atmospheric SO\u2082 column density decreasing by more than one order of magnitude from the equator to the poles in accordance with the observed spatial variations of Io's column densities. Our model produces a strong day-night-asymmetry with modeled column density variations of almost two orders of magnitude at the equator as well as a sub-anti-Jovian hemisphere asymmetry, with maximum dayside column densities of 3.7 x 10¹\u2076 cm\u207b² for the sub-Jovian and 8.5 x 10¹\u2076 cm\u207b² for the anti-Jovian hemisphere. Both are consistent with the observed temporal and large-scale longitudinal variation of Io's atmosphere. We find that the diurnal variations of the surface temperature affect the subsurface structure up to a depth of 0.6 m. Furthermore, we quantify seasonal effects with Io having a northern summer close to perihelion and a northern winter close to aphelion. Finally, we found that at Io's anomalous warm polar regions a conductive heat flux of at least 1.2 Wm\u207b² is necessary to reach surface temperatures consistent with observations.
",
"doi": "10.1029/2024je008869",
"issn": "2169-9097",
"publisher": "American Geophysical Union",
"publication": "Journal of Geophysical Research: Planets",
"publication_date": "2025-07",
"series_number": "7",
"volume": "130",
"issue": "7",
"pages": "e2024JE008869"
},
{
"id": "authors:rex3x-6w925",
"collection": "authors",
"collection_id": "rex3x-6w925",
"cite_using_url": "https://authors.library.caltech.edu/records/rex3x-6w925",
"type": "article",
"title": "Doppler shifted transient sodium detection by KECK/HIRES",
"author": [
{
"family_name": "Unni",
"given_name": "Athira",
"orcid": "0000-0001-6093-5455"
},
{
"family_name": "Oza",
"given_name": "Apurva V.",
"orcid": "0000-0002-1655-0715",
"clpid": "Oza-Apurva-V"
},
{
"family_name": "Hoeijmakers",
"given_name": "H. Jens",
"orcid": "0000-0001-8981-6759"
},
{
"family_name": "Seidel",
"given_name": "Julia V.",
"orcid": "0000-0002-7990-9596"
},
{
"family_name": "Sivarani",
"given_name": "Thirupathi",
"orcid": "0000-0003-0891-8994"
},
{
"family_name": "Schmidt",
"given_name": "Carl A.",
"orcid": "0000-0002-6917-3458"
},
{
"family_name": "Kesseli",
"given_name": "Aurora Y.",
"orcid": "0000-0002-3239-5989",
"clpid": "Kesseli-Aurora-Y"
},
{
"family_name": "de\u00a0Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Baker",
"given_name": "Ashley D.",
"orcid": "0000-0002-6525-7013",
"clpid": "Baker-Ashley-D"
},
{
"family_name": "Gebek",
"given_name": "Andrea",
"orcid": "0000-0002-0206-8231"
},
{
"family_name": "Westram",
"given_name": "Moritz Meyer zu"
},
{
"family_name": "Fisher",
"given_name": "Chloe",
"orcid": "0000-0003-0652-2902"
},
{
"family_name": "Sallum",
"given_name": "Steph",
"orcid": "0000-0001-6871-6775"
},
{
"family_name": "Bestha",
"given_name": "Manjunath",
"orcid": "0009-0002-3354-3549"
},
{
"family_name": "Bello-Arufe",
"given_name": "Aaron",
"orcid": "0000-0003-3355-1223",
"clpid": "Bello-Arufe-Aaron"
}
],
"abstract": "We carried out the first high-resolution transit observations of the exoplanet WASP-49 Ab with Keck/HIRES. Upon custom wavelength calibration we achieve a Doppler RV precision of < 60 m s\u207b¹\u2060. This is an improvement in RV stability of roughly 240 m s\u207b¹ with respect to the instrument standard. We report an average sodium flux residual of ΔF_(NaD)/F*(λ) ~3.2 ± 0.4 per cent (8.0σ\u2060) comparable to previous studies. Interestingly, an average Doppler shift of −6.2 ± 0.5 km s\u207b¹ (12.4σ\u2060) is identified offset from the exoplanet rest frame. The velocity residuals in time trace a blueshift (vΓ,ingress ~ −10.3 ± 1.9 km s\u207b¹\u2060\u2060) to redshift (vΓ,egress ~ + 4.1 ± 1.5 \u2060km s\u207b¹) suggesting the origin of the observed sodium is unlikely from the atmosphere of the planet. The average Na light curves indicate a depth of ΔF_(NaD)/F*(t) ~0.47 ± 0.04 per cent (11.7σ\u2060) enduring ≤ 90 min with a half-max duration of ~40.1 min. Frequent high-resolution spectroscopic observations will be able to characterize the periodicity of the observed Doppler shifts. Considering the origin of the transient sodium gas is of unknown geometry, a co-orbiting natural satellite may be a likely source.
",
"doi": "10.1093/mnrasl/slaf031",
"issn": "1745-3925",
"publisher": "Royal Astronomical Society",
"publication": "Monthly Notices of the Royal Astronomical Society: Letters",
"publication_date": "2025-06",
"series_number": "1",
"volume": "540",
"issue": "1",
"pages": "L48-L53"
},
{
"id": "authors:p8by3-yen49",
"collection": "authors",
"collection_id": "p8by3-yen49",
"cite_using_url": "https://authors.library.caltech.edu/records/p8by3-yen49",
"type": "article",
"title": "Europa's H\u2082O\u2082: Temperature Insensitivity and a Correlation with CO\u2082",
"author": [
{
"family_name": "Wu",
"given_name": "Peiyu",
"orcid": "0000-0002-8690-4910"
},
{
"family_name": "Trumbo",
"given_name": "Samantha K.",
"orcid": "0000-0002-0767-8901"
},
{
"family_name": "Brown",
"given_name": "Michael E.",
"orcid": "0000-0002-8255-0545",
"clpid": "Brown-M-E"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
}
],
"abstract": "\n
H2O2 is part of Europa's water-ice radiolytic cycle and a potential source of oxidants to Europa's subsurface ocean. However, factors controlling the concentration of this critical surface species remain unclear. Though laboratory experiments suggest that Europa's H2O2 should be concentrated in the coldest, most ice-rich regions toward the poles, Keck adaptive optics observations have shown the strongest H2O2 signatures in comparatively warm, salt-bearing terrain at low latitudes. As a result, it was suggested that the local non-ice composition of these terrains—particularly hypothesized enrichments of CO2—may be a more dominant control on H2O2 than temperature or water-ice abundance. Here we use observations of Europa from the NASA Infrared Telescope Facility, Keck Observatory, and JWST to disentangle the potential effects of temperature and composition. In order to isolate the effect of temperature on Europa's H2O2, we use the ground-based observations to assess its response to temperature changes over timescales associated with Europa's daily eclipse and diurnal cycle. We use JWST Cycle 1 data to look for any geographic correlation between Europa's H2O2 and CO2. Changes in Europa's 3.5 μm H2O2 absorption band both from pre- to post-eclipse and across a local day suggest minimal effects of the local temperature on these timescales. In contrast, the JWST observations show a strong positive correlation between Europa's H2O2 and CO2 bands, supporting the previously suggested possibility that the presence of CO2 in the ice may enhance H2O2 concentrations via electron scavenging.
\n
Jupiter's Great Red Spot (GRS) was mapped by the James Webb Space Telescope (JWST)/Mid\u2010Infrared Instrument (4.9–27.9 m) in July and August 2022. These observations took place alongside a suite of visual and infrared observations from; Hubble, JWST/NIRCam, Very Large Telescope/VISIR and amateur observers which provided both spatial and temporal context across the jovian disc. The stratospheric temperature structure retrieved using the NEMESIS software revealed a series of hot\u2010spots above the GRS. These could be the consequence of GRS\u2010induced wave activity. In the troposphere, the temperature structure was used to derive the thermal wind structure of the GRS vortex. These winds were only consistent with the independently determined wind field by JWST/NIRCam at 240 mbar if the altitude of the Hubble\u2010derived winds were located around 1,200 mbar, considerably deeper than previously assumed. No enhancement in ammonia was found within the GRS but a link between elevated aerosol and phosphine abundances was observed within this region. North\u2010south asymmetries were observed in the retrieved temperature, ammonia, phosphine and aerosol structure, consistent with the GRS tilting in the north\u2010south direction. Finally, a small storm was captured north\u2010west of the GRS that displayed a considerable excess in retrieved phosphine abundance, suggestive of vigorous convection. Despite this, no ammonia ice was detected in this region. The novelty of JWST required us to develop custom\u2010made software to resolve challenges in calibration of the data. This involved the derivation of the \"FLT\u20105\" wavelength calibration solution that has subsequently been integrated into the standard calibration pipeline.
",
"doi": "10.1029/2024je008415",
"issn": "2169-9097",
"publisher": "American Geophysical Union",
"publication": "Journal of Geophysical Research: Planets",
"publication_date": "2024-09-27",
"series_number": "10",
"volume": "129",
"issue": "10",
"pages": "e2024JE008415"
},
{
"id": "authors:c4kg0-0sr71",
"collection": "authors",
"collection_id": "c4kg0-0sr71",
"cite_using_url": "https://authors.library.caltech.edu/records/c4kg0-0sr71",
"type": "book_section",
"title": "Characterizing exoplanet atmospheres with SCALES medium-spectral-resolution angular/spectral differential imaging",
"book_title": "Ground-based and Airborne Instrumentation for Astronomy X",
"author": [
{
"family_name": "Desai",
"given_name": "Aditi"
},
{
"family_name": "Sallum",
"given_name": "Stephanie",
"orcid": "0000-0001-6871-6775"
},
{
"family_name": "Banyal",
"given_name": "Ravinder K.",
"orcid": "0000-0003-0799-969X"
},
{
"family_name": "Batalha",
"given_name": "Natalie"
},
{
"family_name": "Batalha",
"given_name": "Natasha"
},
{
"family_name": "Blake",
"given_name": "Geoffrey A.",
"orcid": "0000-0003-0787-1610",
"clpid": "Blake-G-A"
},
{
"family_name": "Brandt",
"given_name": "Timothy D."
},
{
"family_name": "Briesemeister",
"given_name": "Zack"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168"
},
{
"family_name": "Eisner",
"given_name": "Joshua A."
},
{
"family_name": "Fong",
"given_name": "Wen-fai",
"orcid": "0000-0002-7374-935X"
},
{
"family_name": "Greene",
"given_name": "Tom"
},
{
"family_name": "Honda",
"given_name": "Mitsuhiko",
"orcid": "0000-0002-6172-9124"
},
{
"family_name": "Kain",
"given_name": "Isabel",
"orcid": "0000-0001-9894-5229"
},
{
"family_name": "Kilpatrick",
"given_name": "Charlie"
},
{
"family_name": "Lach",
"given_name": "Mackenzie"
},
{
"family_name": "Liu",
"given_name": "Mike"
},
{
"family_name": "Macintosh",
"given_name": "Bruce A."
},
{
"family_name": "Martinez",
"given_name": "Raquel"
},
{
"family_name": "Mawet",
"given_name": "Dimitri",
"orcid": "0000-0002-8895-4735",
"clpid": "Mawet-D"
},
{
"family_name": "Miles",
"given_name": "Brittany E."
},
{
"family_name": "Morley",
"given_name": "Caroline"
},
{
"family_name": "Powell",
"given_name": "Diana"
},
{
"family_name": "Sheehan",
"given_name": "Patrick"
},
{
"family_name": "Skemer",
"given_name": "Andrew",
"orcid": "0000-0001-6098-3924"
},
{
"family_name": "Stelter",
"given_name": "R. D.",
"orcid": "0000-0003-4549-0210"
},
{
"family_name": "Stone",
"given_name": "Jordan"
},
{
"family_name": "Surya",
"given_name": "Arun",
"orcid": "0000-0002-9967-0391"
},
{
"family_name": "Thirupathi",
"given_name": "Sivarani",
"orcid": "0000-0003-0891-8994"
},
{
"family_name": "Wagner",
"given_name": "Kevin"
},
{
"family_name": "Zhou",
"given_name": "Yifan"
}
],
"editor": [
{
"family_name": "Vernet",
"given_name": "Jo\u00ebl R."
},
{
"family_name": "Bryant",
"given_name": "Julia J."
},
{
"family_name": "Motohara",
"given_name": "Kentaro"
}
],
"abstract": "SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) is a high-contrast lenslet-based integral field spectrograph (IFS) designed to characterize exoplanet atmospheres in the 2 - 5 micron wavelength range. The SCALES medium-resolution mode provides the ability to characterize exoplanets at increased spectral resolution via the use of a lenslet subarray with a 0.34 x 0.36 arcsecond field of view and an image slicer. We use the SCALES simulator scalessim to generate high-fidelity mock observations of planets in the mediumresolution mode that include realistic Keck adaptive optics performance, as well as other atmospheric and instrumental noise effects, to simulate planet detections, and then employ angular differential imaging to extract the planet spectra. Analyzing the recovered spectra from these simulations allows us to quantify the effects of systematic noise sources on planet characterization, in particular residual speckle noise following angular differential data processing. We use these simulated recovered spectra to explore SCALES' ability to constrain molecular abundances and disequilibrium chemistry in giant exoplanet atmospheres.",
"doi": "10.1117/12.3020521",
"isbn": "9781510675155",
"publisher": "SPIE",
"publication": "Ground-based and Airborne Instrumentation for Astronomy X",
"publication_date": "2024-09-17",
"volume": "13096",
"pages": "130969C"
},
{
"id": "authors:85vzw-a1a13",
"collection": "authors",
"collection_id": "85vzw-a1a13",
"cite_using_url": "https://authors.library.caltech.edu/records/85vzw-a1a13",
"type": "article",
"title": "Ionospheric irregularities at Jupiter observed by JWST",
"author": [
{
"family_name": "Melin",
"given_name": "Henrik",
"orcid": "0000-0001-5971-2633"
},
{
"family_name": "O'Donoghue",
"given_name": "J.",
"orcid": "0000-0002-4218-1191",
"clpid": "O'Donoghue-James"
},
{
"family_name": "Moore",
"given_name": "L.",
"orcid": "0000-0003-4481-9862",
"clpid": "Moore-Luke"
},
{
"family_name": "Stallard",
"given_name": "T. S.",
"orcid": "0000-0003-3990-670X",
"clpid": "Stafford-Tom-S"
},
{
"family_name": "Fletcher",
"given_name": "L. N.",
"clpid": "Fletcher-L-N"
},
{
"family_name": "Roman",
"given_name": "M. T.",
"orcid": "0000-0001-8206-2165",
"clpid": "Roman-Michael-Thomas"
},
{
"family_name": "Harkett",
"given_name": "J.",
"orcid": "0009-0007-1223-8752",
"clpid": "Harkett-Jake"
},
{
"family_name": "King",
"given_name": "O. R. T.",
"clpid": "King-O-R-T"
},
{
"family_name": "Thomas",
"given_name": "E. M.",
"orcid": "0000-0002-5773-6110",
"clpid": "Thomas-Emma-M"
},
{
"family_name": "Wang",
"given_name": "R.",
"orcid": "0000-0002-4563-8919",
"clpid": "Wang-Ruoyan"
},
{
"family_name": "Tiranti",
"given_name": "P. I.",
"orcid": "0000-0001-7339-9495",
"clpid": "Tiranti-Paola"
},
{
"family_name": "Knowles",
"given_name": "K. L.",
"orcid": "0000-0001-5055-8115",
"clpid": "Knowles-Katie-L"
},
{
"family_name": "de Pater",
"given_name": "I.",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Fouchet",
"given_name": "T.",
"orcid": "0000-0001-9040-8285",
"clpid": "Fouchet-Thierry"
},
{
"family_name": "Fry",
"given_name": "P. H.",
"orcid": "0000-0002-7367-6541",
"clpid": "Fry-Patrick-H"
},
{
"family_name": "Wong",
"given_name": "M. H.",
"orcid": "0000-0003-2804-5086",
"clpid": "Wong-Michael-H"
},
{
"family_name": "Holler",
"given_name": "B. J.",
"orcid": "0000-0002-6117-0164",
"clpid": "Holler-Bryan-J"
},
{
"family_name": "Hueso",
"given_name": "R.",
"orcid": "0000-0003-0169-123X",
"clpid": "Hueso-Ricardo"
},
{
"family_name": "James",
"given_name": "M. K.",
"orcid": "0000-0002-5699-6121",
"clpid": "James-Matthew-K"
},
{
"family_name": "Orton",
"given_name": "G. S.",
"orcid": "0000-0001-7871-2823",
"clpid": "Orton-Glenn-S"
},
{
"family_name": "Mura",
"given_name": "A.",
"orcid": "0000-0002-4552-4292",
"clpid": "Mura-Alessandro"
},
{
"family_name": "S\u00e1nchez-Lavega",
"given_name": "A.",
"orcid": "0000-0001-7234-7634",
"clpid": "S\u00e1nchez-Lavega-Agust\u00edn"
},
{
"family_name": "Lellouch",
"given_name": "E.",
"orcid": "0000-0001-7168-1577",
"clpid": "Lellouch-Emmanuel"
},
{
"family_name": "de Kleer",
"given_name": "K.",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Showalter",
"given_name": "M. R.",
"orcid": "0000-0002-8580-4053",
"clpid": "Showalter-Mark-R"
}
],
"abstract": "\n
\n
Jupiter’s upper atmosphere is composed of a neutral thermosphere and charged ionosphere. In the latter, the dominant molecular ion H3+ emits in the near-infrared, allowing for the remote exploration of the physical properties of the upper atmosphere. However, the Jovian low-latitude ionosphere remains largely unexplored because H3+ emissions from this region are faint and spectrally entangled with bright neutral species, such as CH4. Here, we present James Webb Space Telescope H3+ observations of Jupiter’s low-latitude ionosphere in the region of the Great Red Spot, showing unexpected small-scale intensity features such as arcs, bands and spots. Our observations may imply that the low-latitude ionosphere of Jupiter is strongly coupled to the lower atmosphere via gravity waves that superimpose to produce this complex and intricate morphology.
\n
\n
\n
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes on Io's surface have been monitored from both spacecraft and ground-based telescopes. Here, we present the highest spatial resolution images of Io ever obtained from a ground-based telescope. These images, acquired by the SHARK-VIS instrument on the Large Binocular Telescope, show evidence of a major resurfacing event on Io's trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images show that a plume deposit from a powerful eruption at Pillan Patera has covered part of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io's surface using adaptive optics at visible wavelengths.
\n
\n
Ground-based observations of \"Barbarian\" L-type asteroids at 1–2.5 μm indicate that their near-infrared spectra are dominated by the mineral spinel, which has been attributed to a high abundance of calcium-aluminum inclusions (CAIs)—the first solids to condense out of the protoplanetary disk during the formation of the solar system. However, the spectral properties of these asteroids from 2.5–5 μm, a wavelength region that covers signatures of hydrated minerals, water, and organics, have not yet been explored. Here, we present 2–5 μm reflectance spectra of five spinel-rich asteroids obtained with the NIRSpec instrument on the James Webb Space Telescope. All five targets exhibit a ∼2.85 μm absorption feature with a band depth of 3%–6% that appears correlated in strength with that of the 2 μm spinel absorption feature. The shape and position of the 2.85 μm feature are not a good match to the 2.7 μm feature commonly seen in carbonaceous CM meteorites or C-type asteroids. The closest spectral matches are to the Moon and Vesta, suggesting commonalities in aqueous alteration across silicate bodies, infall of hydrated material, and/or space weathering by solar wind H implantation. Lab spectra of CO/CV chondrites, CAIs, as well as the minerals cronstedtite and spinel, also show a similar feature, providing clues into the origin of the 2.85 μm feature.
\n
Jupiter’s moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io’s inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass loss history, and thus records information about its evolution. We used millimeter observations of Io’s atmosphere to measure sulfur isotopes in gaseous SO2 and SO, and chlorine isotopes in gaseous NaCl and KCl. We find 34S/32S = 0.0595 ± 0.0038 (equivalent to δ34S = +347 ± 86‰), which is highly enriched compared to average Solar System values and indicates that Io has lost 94 to 99% of its available sulfur. Our measurement of 37Cl/35Cl = 0.403 ± 0.028 (δ37Cl = +263 ± 88‰) shows that chlorine is similarly enriched. These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.
",
"doi": "10.1126/science.adj0625",
"issn": "0036-8075",
"publisher": "American Association for the Advancement of Science",
"publication": "Science",
"publication_date": "2024-05-10",
"series_number": "6696",
"volume": "384",
"issue": "6696",
"pages": "682-687"
},
{
"id": "authors:2n2a7-rbh90",
"collection": "authors",
"collection_id": "2n2a7-rbh90",
"cite_using_url": "https://authors.library.caltech.edu/records/2n2a7-rbh90",
"type": "article",
"title": "Observations of Titan's Stratosphere during Northern Summer: Temperatures, CH\u2083CN and CH\u2083D Abundances",
"author": [
{
"family_name": "Thelen",
"given_name": "Alexander E.",
"orcid": "0000-0002-8178-1042",
"clpid": "Thelen-Alexander-E"
},
{
"family_name": "Nixon",
"given_name": "Conor A.",
"orcid": "0000-0001-9540-9121",
"clpid": "Nixon-Conor-A"
},
{
"family_name": "Cordiner",
"given_name": "Martin A.",
"orcid": "0000-0001-8233-2436",
"clpid": "Cordiner-Martin-A"
},
{
"family_name": "Lellouch",
"given_name": "Emmanuel",
"orcid": "0000-0001-7168-1577",
"clpid": "Lellouch-Emmanuel"
},
{
"family_name": "Vinatier",
"given_name": "Sandrine",
"orcid": "0000-0001-5541-2502",
"clpid": "Vinatier-Sandrine"
},
{
"family_name": "Teanby",
"given_name": "Nicholas A.",
"orcid": "0000-0003-3108-5775",
"clpid": "Teanby-Nicholas-A"
},
{
"family_name": "Butler",
"given_name": "Bryan",
"orcid": "0000-0002-5344-820X",
"clpid": "Butler-Bryan"
},
{
"family_name": "Charnley",
"given_name": "Steven B.",
"orcid": "0000-0001-6752-5109",
"clpid": "Charnley-Steven-B"
},
{
"family_name": "Cosentino",
"given_name": "Richard G.",
"orcid": "0000-0003-3047-615X",
"clpid": "Cosentino-Richard-G"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Irwin",
"given_name": "Patrick G. J.",
"orcid": "0000-0002-6772-384X",
"clpid": "Irwin-Patrick-G-J"
},
{
"family_name": "Gurwell",
"given_name": "Mark A.",
"orcid": "0000-0003-0685-3621",
"clpid": "Gurwell-Mark-A"
},
{
"family_name": "Kisiel",
"given_name": "Zbigniew",
"orcid": "0000-0002-2570-3154",
"clpid": "Kisiel-Zbigniew"
},
{
"family_name": "Moreno",
"given_name": "Raphael",
"orcid": "0000-0002-9171-2702",
"clpid": "Moreno-Raphael"
}
],
"abstract": "\n
Titan's atmospheric composition and dynamical state have previously been studied over numerous epochs by both ground- and space-based facilities. However, stratospheric measurements remain sparse during Titan's northern summer and fall. The lack of seasonal symmetry in observations of Titan's temperature field and chemical abundances raises questions about the nature of the middle atmosphere's meridional circulation and evolution over Titan's 29 yr seasonal cycle that can only be answered through long-term monitoring campaigns. Here, we present maps of Titan's stratospheric temperature, acetonitrile (or methyl cyanide; CH3CN) abundance, and monodeuterated methane (CH3D) abundance following Titan's northern summer solstice obtained with Band 9 (∼0.43 mm) Atacama Large Millimeter/submillimeter Array observations. We find that increasing temperatures toward high southern latitudes, currently in winter, resemble those observed during Titan's northern winter by the Cassini mission. Acetonitrile abundances have changed significantly since previous (sub)millimeter observations, and we find that the species is now highly concentrated at high southern latitudes. The stratospheric CH3D content is found to range between 4 and 8 ppm in these observations, and we infer the CH4 abundance to vary between ∼0.9% and 1.6% through conversion with previously measured D/H values. A global value of CH4 = 1.15% was retrieved, lending further evidence to the temporal and spatial variability of Titan's stratospheric methane when compared with previous measurements. Additional observations are required to determine the cause and magnitude of stratospheric enhancements in methane during these poorly understood seasons on Titan.
\n
\n
Stable isotope fractionation of sulfur offers a window into Io's tidal heating history, which is difficult to constrain because Io's dynamic atmosphere and high resurfacing rates leave it with a young surface. We constructed a numerical model to describe the fluxes in Io's sulfur cycle using literature constraints on rates and isotopic fractionations of relevant processes. Combining our numerical model with measurements of the 34S/32S ratio in Io's atmosphere, we constrain the rates for the processes that move sulfur between reservoirs and model the evolution of sulfur isotopes over time. Gravitational stratification of SO2 in the upper atmosphere, leading to a decrease in 34S/32S with increasing altitude, is the main cause of sulfur isotopic fractionation associated with loss to space. Efficient recycling of the atmospheric escape residue into the interior is required to explain the 34S/32S enrichment magnitude measured in the modern atmosphere. We hypothesize this recycling occurs by SO2 surface frost burial and SO2 reaction with crustal rocks, which founder into the mantle and/or mix with mantle-derived magmas as they ascend. Therefore, we predict that magmatic SO2 plumes vented from the mantle to the atmosphere will have lower 34S/32S than the ambient atmosphere, yet are still significantly enriched compared to solar-system average sulfur. Observations of atmospheric variations in 34S/32S with time and/or location could reveal the average mantle melting rate and hence whether the current tidal heating rate is anomalous compared to Io's long-term average. Our modeling suggests that tides have heated Io for >1.6 Gyr if Io today is representative of past Io.
\n
\n
We present best-fit values of porosity—and the corresponding effective thermal inertiae—determined from three different depths in Europa's near-subsurface (∼1–20 cm). The porosity of the upper ∼20 cm of Europa's subsurface varies between 75% and 50% (Γeff ≈ 50–140 J m−2 K−1 s−1/2) on the leading hemisphere and 50%–40% (Γeff ≈ 140–180 J m−2 K−1 s−1/2) on the trailing hemisphere. Residual maps produced by comparison with these models reveal thermally anomalous features that cannot be reproduced by globally homogeneous porosity models. These regions are compared to Europa's surface terrain and known compositional variations. We find that some instances of warm thermal anomalies are co-located with known geographical or compositional features on both the leading and trailing hemisphere; cool temperature anomalies are well correlated with surfaces previously observed to contain pure, crystalline water ice and the expansive rays of Pwyll crater. Anomalous regions correspond to locations with subsurface properties different from those of our best-fit models, such as potentially elevated thermal inertia, decreased emissivity, or more porous regolith. We also find that ALMA observations at ∼3 mm sound below the thermal skin depth of Europa (∼10–15 cm) for a range of porosity values, and thus do not exhibit features indicative of diurnal variability or residuals similar to other frequency bands. Future observations of Europa at higher angular resolution may reveal additional locations of variable subsurface thermophysical properties, while those at other wavelengths will inform our understanding of the regolith compaction length and the effects of external processes on the shallow subsurface.
\n
Using archival near-infrared observations from the Keck and Lick Observatories and the Hubble Space Telescope, we document the evolution of Neptune’s cloud activity from 1994 to 2022. We calculate the fraction of Neptune’s disk that contained clouds, as well as the average brightness of both cloud features and cloud-free background over the planet’s disk. We observe cloud activity and brightness maxima during 2002 and 2015, and minima during 2007 and 2020, the latter of which is particularly deep. Neptune’s lack of cloud activity in 2020 is characterized by a near-total loss of clouds at mid-latitudes and continued activity at the South Pole. We find that the periodic variations in Neptune’s disk-averaged brightness in the near-infrared H (1.6μm), K (2.1μm), FWCH4P15 (893 nm), F953N (955 nm), FWCH4P15 (965 nm), and F845M (845 nm) bands are dominated by discrete cloud activity, rather than changes in the background haze. The clear positive correlation we find between cloud activity and Solar Lyman-Alpha (121.56 nm) irradiance lends support to the theory that the periodicity in Neptune’s cloud activity results from photochemical cloud/haze production triggered by Solar ultraviolet emissions.
",
"doi": "10.1016/j.icarus.2023.115667",
"issn": "0019-1035",
"publisher": "Elsevier",
"publication": "Icarus",
"publication_date": "2023-11-01",
"volume": "404",
"pages": "115667"
},
{
"id": "authors:1hr5q-rmg96",
"collection": "authors",
"collection_id": "1hr5q-rmg96",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230725-500500000.16",
"type": "article",
"title": "Drift rates of major Neptunian features between 2018 and 2021",
"author": [
{
"family_name": "Chavez",
"given_name": "Erandi",
"orcid": "0000-0003-4143-9717",
"clpid": "Chavez-Erandi"
},
{
"family_name": "Redwing",
"given_name": "Erin",
"clpid": "Redwing-Erin"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-I"
},
{
"family_name": "Hueso",
"given_name": "Ricardo",
"clpid": "Hueso-Ricardo"
},
{
"family_name": "Molter",
"given_name": "Edward M.",
"clpid": "Molter-Edward-M"
},
{
"family_name": "Wong",
"given_name": "Michael H.",
"orcid": "0000-0003-2804-5086",
"clpid": "Wong-Michael-H"
},
{
"family_name": "Alvarez",
"given_name": "Carlos",
"clpid": "Alvarez-Carlos"
},
{
"family_name": "Gates",
"given_name": "Elinor",
"orcid": "0000-0002-3739-0423",
"clpid": "Gates-Elinor"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Aycock",
"given_name": "Joel",
"clpid": "Aycock-Joel"
},
{
"family_name": "Mcilroy",
"given_name": "Jason",
"clpid": "Mcilroy-Jason"
},
{
"family_name": "Pelletier",
"given_name": "John",
"clpid": "Pelletier-John"
},
{
"family_name": "Ridenour",
"given_name": "Anthony",
"clpid": "Ridenour-Anthony"
},
{
"family_name": "S\u00e1nchez-Lavega",
"given_name": "Agust\u00edn",
"clpid": "S\u00e1nchez-Lavega-Agust\u00edn"
},
{
"family_name": "Rojas",
"given_name": "Jose F\u00e9lix",
"clpid": "Rojas-Jose-F\u00e9lix"
},
{
"family_name": "Stickel",
"given_name": "Terry",
"clpid": "Stickel-Terry"
}
],
"abstract": "Using near-infrared observations of Neptune from the Keck and Lick Observatories, and the Hubble Space Telescope in combination with amateur datasets, we calculated the drift rates of prominent infrared-bright cloud features on Neptune between 2018 and 2021. These features had lifespans of ~ 1 day to \u2265 1 month and were located at mid-latitudes and near the south pole. Our observations permitted determination of drift rates via feature tracking. These drift rates were compared to three zonal wind profiles describing Neptune's atmosphere determined from features tracked in H band (1.6 \u00b5m), K' band (2.1 \u00b5m), and Voyager 2 data at visible wavelengths. Features near -70 deg measured in the F845M filter (845 nm) were particularly consistent with the K' wind profile. The southern mid-latitudes hosted multiple features whose lifespans were \u2265 1 month, providing evidence that these latitudes are a region of high stability in Neptune's atmosphere. We also used HST F467M (467 nm) data to analyze a dark, circumpolar wave at -60\u00b0 latitude observed on Neptune since the Voyager 2 era. Its drift rate in recent years (2019\u20132021) is 4.866 \u00b1 0.009\u00b0/day. This is consistent with previous measurements by Karkoschka (2011), which predict a 4.858 \u00b1 0.022\u00b0/day drift rate during these years. It also gained a complementary bright band just to the north.",
"doi": "10.1016/j.icarus.2023.115604",
"issn": "0019-1035",
"publisher": "Elsevier",
"publication": "Icarus",
"publication_date": "2023-09-01",
"volume": "401",
"pages": "Art. No. 115604"
},
{
"id": "authors:xyh4t-zvt72",
"collection": "authors",
"collection_id": "xyh4t-zvt72",
"cite_using_url": "https://authors.library.caltech.edu/records/xyh4t-zvt72",
"type": "article",
"title": "Hydrogen peroxide at the poles of Ganymede",
"author": [
{
"family_name": "Trumbo",
"given_name": "Samantha K.",
"orcid": "0000-0002-0767-8901",
"clpid": "Trumbo-Samantha-K"
},
{
"family_name": "Brown",
"given_name": "Michael E.",
"orcid": "0000-0002-8255-0545",
"clpid": "Brown-M-E"
},
{
"family_name": "Bockel\u00e9e-Morvan",
"given_name": "Dominique",
"orcid": "0000-0002-8130-0974",
"clpid": "Bockel\u00e9e-Morvan-Dominique"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168"
},
{
"family_name": "Fouchet",
"given_name": "Thierry",
"orcid": "0000-0001-9040-8285",
"clpid": "Fouchet-Thierry"
},
{
"family_name": "Wong",
"given_name": "Michael H.",
"orcid": "0000-0003-2804-5086",
"clpid": "Wong-Michael-H"
},
{
"family_name": "Cazaux",
"given_name": "St\u00e9phanie",
"orcid": "0000-0003-0320-3578",
"clpid": "Cazaux-St\u00e9phanie"
},
{
"family_name": "Fletcher",
"given_name": "Leigh N.",
"orcid": "0000-0001-5834-9588",
"clpid": "Fletcher-Leigh-N"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Lellouch",
"given_name": "Emmanuel",
"orcid": "0000-0001-7168-1577",
"clpid": "Lellouch-Emmanuel"
},
{
"family_name": "Mura",
"given_name": "Alessandro",
"orcid": "0000-0002-4552-4292",
"clpid": "Mura-Alessandro"
},
{
"family_name": "Poch",
"given_name": "Olivier",
"orcid": "0000-0001-6777-8296",
"clpid": "Poch-Olivier"
},
{
"family_name": "Quirico",
"given_name": "Eric",
"orcid": "0000-0003-2768-0694",
"clpid": "Quirico-Eric"
},
{
"family_name": "Rodriguez-Ovalle",
"given_name": "Pablo",
"orcid": "0000-0003-2594-2128",
"clpid": "Rodriguez-Ovalle-Pablo"
},
{
"family_name": "Showalter",
"given_name": "Mark R.",
"orcid": "0000-0002-8580-4053",
"clpid": "Showalter-Mark-R"
},
{
"family_name": "Tiscareno",
"given_name": "Matthew S.",
"orcid": "0000-0002-2736-3667",
"clpid": "Tiscareno-Matthew-S"
},
{
"family_name": "Tosi",
"given_name": "Federico",
"orcid": "0000-0003-4002-2434",
"clpid": "Tosi-Federico"
}
],
"abstract": "Ganymede is the only satellite in the solar system known to have an intrinsic magnetic field. Interactions between this field and the Jovian magnetosphere are expected to funnel most of the associated impinging charged particles, which radiolytically alter surface chemistry across the Jupiter system, to Ganymede's polar regions. Using observations obtained with JWST as part of the Early Release Science program exploring the Jupiter system, we report the discovery of hydrogen peroxide, a radiolysis product of water ice, specifically constrained to the high latitudes. This detection directly implies radiolytic modification of the polar caps by precipitation of Jovian charged particles along partially open field lines within Ganymede's magnetosphere. Stark contrasts between the spatial distribution of this polar hydrogen peroxide, those of Ganymede's other radiolytic oxidants, and that of hydrogen peroxide on neighboring Europa have important implications for understanding water-ice radiolysis throughout the solar system.",
"doi": "10.1126/sciadv.adg3724",
"pmcid": "PMC10361591",
"issn": "2375-2548",
"publisher": "American Association for the Advancement of Science",
"publication": "Science Advances",
"publication_date": "2023-07-21",
"series_number": "29",
"volume": "9",
"issue": "29",
"pages": "eadg3724"
},
{
"id": "authors:k2ywp-g5y72",
"collection": "authors",
"collection_id": "k2ywp-g5y72",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230221-191753000.3",
"type": "article",
"title": "The Optical Aurorae of Europa, Ganymede, and Callisto",
"author": [
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Milby",
"given_name": "Zachariah",
"orcid": "0000-0001-5683-0095",
"clpid": "Milby-Zachariah"
},
{
"family_name": "Schmidt",
"given_name": "Carl",
"orcid": "0000-0002-6917-3458",
"clpid": "Schmidt-Carl"
},
{
"family_name": "Camarca",
"given_name": "Maria",
"orcid": "0000-0003-3887-4080",
"clpid": "Camarca-Maria"
},
{
"family_name": "Brown",
"given_name": "Michael E.",
"orcid": "0000-0002-8255-0545",
"clpid": "Brown-M-E"
}
],
"abstract": "The tenuous atmospheres of the Galilean satellites are sourced from their surfaces and produced by a combination of plasma-surface interactions and thermal processes. Even though they are thin, these atmospheres can be studied via their auroral emissions, and most work to date has focused on their aurorae at UV wavelengths. Here we present the first detections of the optical aurorae of Ganymede and Callisto, as well as detections of new optical auroral lines at Europa, based on observations of the targets over 10 Jupiter eclipses from 1998 to 2021 with Keck/HIRES. We present measurements of O i emission at 6300/6364, 5577, 7774, and 8446 \u00c5 and place upper limits on hydrogen at 6563 \u00c5. These constitute the first detections of emissions at 7774 and 8446 \u00c5 at a planetary body other than Earth. The simultaneous measurement of multiple emission lines provides robust constraints on atmospheric composition. We find that the eclipse atmospheres of Europa and Ganymede are composed predominantly of O\u2082, with average column densities of (4.1 \u00b1 0.1) \u00d7 101\u2082 cm\u207b\u00b2 and (4.7 \u00b1 0.1) \u00d7 10\u2082 cm\u207b\u00b2, respectively. We find weak evidence for H2O in Europa's bulk atmosphere at an H\u2082O/O\u2082 ratio of \u223c0.25, and place only an upper limit on H\u2082O in Ganymede's bulk atmosphere, corresponding to H\u2082O/O\u2082 < 0.6. The column density of O\u2082 derived for Callisto is (4.0 \u00b1 0.9) \u00d7 10\u00b9\u2075 cm\u207b\u00b2 for an assumed electron density of 0.15 cm\u207b\u00b3, but electron properties at Callisto's orbit are very poorly constrained.",
"doi": "10.3847/psj/acb53c",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2023-02",
"series_number": "2",
"volume": "4",
"issue": "2",
"pages": "Art. No. 37"
},
{
"id": "authors:x951r-haf41",
"collection": "authors",
"collection_id": "x951r-haf41",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230221-191105000.1",
"type": "article",
"title": "Io's Optical Aurorae in Jupiter's Shadow",
"author": [
{
"family_name": "Schmidt",
"given_name": "Carl",
"orcid": "0000-0002-6917-3458",
"clpid": "Schmidt-Carl"
},
{
"family_name": "Sharov",
"given_name": "Mikhail",
"orcid": "0000-0003-3047-5368",
"clpid": "Sharov-Mikhail"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Schneider",
"given_name": "Nick",
"orcid": "0000-0001-6720-5519",
"clpid": "Schneider-Nicholas"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Phipps",
"given_name": "Phillip H.",
"orcid": "0000-0002-4323-4400",
"clpid": "Phipps-Phillip-H"
},
{
"family_name": "Conrad",
"given_name": "Albert",
"orcid": "0000-0003-2872-0061",
"clpid": "Conrad-Albert"
},
{
"family_name": "Moore",
"given_name": "Luke",
"clpid": "Moore-Luke"
},
{
"family_name": "Withers",
"given_name": "Paul",
"orcid": "0000-0003-3084-4581",
"clpid": "Withers-Paul"
},
{
"family_name": "Spencer",
"given_name": "John",
"orcid": "0000-0003-4452-8109",
"clpid": "Spencer-John-R"
},
{
"family_name": "Morgenthaler",
"given_name": "Jeff",
"orcid": "0000-0003-3716-3455",
"clpid": "Morgenthaler-Jeffrey-P"
},
{
"family_name": "Ilyin",
"given_name": "Ilya",
"orcid": "0000-0002-0551-046X",
"clpid": "Ilyin-Ilya"
},
{
"family_name": "Strassmeier",
"given_name": "Klaus",
"orcid": "0000-0002-6192-6494",
"clpid": "Strassmeier-Klaus-G"
},
{
"family_name": "Veillet",
"given_name": "Christian",
"orcid": "0000-0003-0272-0418",
"clpid": "Veillet-Christian"
},
{
"family_name": "Hill",
"given_name": "John",
"orcid": "0000-0003-2484-3670",
"clpid": "Hill-John-M"
},
{
"family_name": "Brown",
"given_name": "Mike",
"orcid": "0000-0002-8255-0545",
"clpid": "Brown-M-E"
}
],
"abstract": "Decline and recovery timescales surrounding eclipse are indicative of the controlling physical processes in Io's atmosphere. Recent studies have established that the majority of Io's molecular atmosphere, SO\u2082 and SO, condenses during its passage through Jupiter's shadow. The eclipse response of Io's atomic atmosphere is less certain, having been characterized solely by ultraviolet aurorae. Here we explore the response of optical aurorae for the first time. We find oxygen to be indifferent to the changing illumination, with [O i] brightness merely tracking the plasma density at Io's position in the torus. In shadow, line ratios confirm sparse SO\u2082 coverage relative to O, since their collisions would otherwise quench the emission. Io's sodium aurora mostly disappears in eclipse and e-folding timescales, for decline and recovery differ sharply: \u223c10 minutes at ingress and nearly 2 hr at egress. Only ion chemistry can produce such a disparity; Io's molecular ionosphere is weaker at egress due to rapid recombination. Interruption of a NaCl\u207a photochemical pathway best explains Na behavior surrounding eclipse, implying that the role of electron impact ionization is minor relative to photons. Auroral emission is also evident from potassium, confirming K as the major source of far red emissions seen with spacecraft imaging at Jupiter. In all cases, direct electron impact on atomic gas is sufficient to explain the brightness without invoking significant dissociative excitation of molecules. Surprisingly, the nonresponse of O and rapid depletion of Na is opposite the temporal behavior of their SO\u2082 and NaCl parent molecules during Io's eclipse phase.",
"doi": "10.3847/psj/ac85b0",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2023-02",
"series_number": "2",
"volume": "4",
"issue": "2",
"pages": "Art. No. 36"
},
{
"id": "authors:ts8yx-nze22",
"collection": "authors",
"collection_id": "ts8yx-nze22",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230615-812830000.16",
"type": "article",
"title": "Perspective: The Future Exploration of Io",
"author": [
{
"family_name": "Keane",
"given_name": "James Tuttle",
"orcid": "0000-0002-4803-5793",
"clpid": "Keane-James-Tuttle"
},
{
"family_name": "de Kleer",
"given_name": "Katherine R.",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Spencer",
"given_name": "John",
"orcid": "0000-0003-4452-8109",
"clpid": "Spencer-John-R"
}
],
"abstract": "Io is one of the best natural laboratories in the Solar System to study the intertwined processes of tidal heating, extreme volcanism, and atmospheric\u2013magnetosphere\u2013surface interactions. While substantial advances can be made with forthcoming ground- and space-based observatories, many outstanding questions can only be addressed with in situ measurements at Io. Several spacecraft will explore the Jupiter system in the next decade, but their capabilities to investigate Io are limited. A dedicated Io mission is necessary to capitalize on Io's scientific potential. Previous Io mission concepts have spanned the gamut, including small spacecraft, multiple-flyby missions, orbiters, and landers. New technologies, including advanced solar power and radiation hardening, make Io exploration more tractable, and the potential for contemporaneous measurements from multiple spacecraft in the Jupiter system make a modern Io mission all the more compelling.",
"doi": "10.2138/gselements.18.6.399",
"issn": "1811-5217",
"publisher": "Mineralogical Society of America",
"publication": "Elements",
"publication_date": "2022-12",
"series_number": "6",
"volume": "18",
"issue": "6",
"pages": "399-404"
},
{
"id": "authors:f8gh7-yq855",
"collection": "authors",
"collection_id": "f8gh7-yq855",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230203-893794600.50",
"type": "article",
"title": "NaCl and KCl in Io's Atmosphere",
"author": [
{
"family_name": "Redwing",
"given_name": "Erin",
"orcid": "0000-0002-5595-3808",
"clpid": "Redwing-Erin"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Luszcz-Cook",
"given_name": "Statia",
"orcid": "0000-0001-9867-9119",
"clpid": "Luszcz-Cook-Statia"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Moullet",
"given_name": "Arielle",
"orcid": "0000-0002-9820-1032",
"clpid": "Moullet-Arielle"
},
{
"family_name": "Rojo",
"given_name": "Patricio M.",
"orcid": "0000-0002-1607-6443",
"clpid": "Rojo-Patricio-M"
}
],
"abstract": "We present the first comprehensive study of NaCl and KCl gases in Io's atmosphere in order to investigate their characteristics and infer properties of Io's volcanoes and subsurface magma chambers. In this work, we compile all past spectral line observations of NaCl and KCl in Io's atmosphere from the Atacama Large Millimeter/submillimeter Array and use atmospheric models to constrain the physical properties of the gases on several dates between 2012 and 2018. NaCl and KCl appear to be largely spatially confined, and for observations with high spectral resolution, the temperatures are high (\u223c500\u20131000 K), implying a volcanic origin. The ratio of NaCl:KCl was found to be \u223c5\u20136 in 2015 June and \u223c3.5\u201310 in 2016 June, which is consistent with predictions based on observations of Io's extended atmosphere and less than half the Na/K ratio in chondrites. Assuming these gases are volcanic in origin, these ratios imply a magma temperature of \u223c1300 K, such that the magma will preferentially outgas KCl over NaCl.",
"doi": "10.3847/psj/ac9784",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2022-10",
"series_number": "10",
"volume": "3",
"issue": "10",
"pages": "Art. No. 238"
},
{
"id": "authors:6jjhb-f2168",
"collection": "authors",
"collection_id": "6jjhb-f2168",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220520-512509000",
"type": "article",
"title": "The Heterogeneous Surface of Asteroid (16) Psyche",
"author": [
{
"family_name": "Cambioni",
"given_name": "Saverio",
"orcid": "0000-0001-6294-4523",
"clpid": "Cambioni-Saverio"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Shepard",
"given_name": "Michael",
"orcid": "0000-0002-8441-2488",
"clpid": "Shepard-Michael-K"
}
],
"abstract": "Main-belt asteroid (16) Psyche is the largest M-type asteroid, a class of object classically thought to be the metal cores of differentiated planetesimals and the parent bodies of the iron meteorites. de Kleer, Cambioni, and Shepard (2021, https://doi.org/10.3847/psj/ac01ec) presented new data from the Atacama Large Millimeter Array (ALMA), from which they derived a global best-fit thermal inertia and dielectric constant for Psyche, proxies for regolith particle size, porosity, and/or metal content, and observed thermal anomalies that could not be explained by surface albedo variations only. Motivated by this, here we fit a model to the same ALMA data set that allows dielectric constant and thermal inertia to vary across the surface. We find that Psyche has a heterogeneous surface in both dielectric constant and thermal inertia but, intriguingly, we do not observe a direct correlation between these two properties over the surface. We explain the heterogeneity in dielectric constant as being due to variations in the relative abundance of metal and silicates. Furthermore, we observe that the lowlands of a large depression in Psyche's shape have distinctly lower thermal inertia than the surrounding highlands. We propose that the latter could be explained by a thin mantle of fine regolith, fractured bedrock, and/or implanted silicate-rich materials covering an otherwise metal-rich surface. All these scenarios are indicative of a collisionally evolved world.",
"doi": "10.1029/2021je007091",
"issn": "2169-9097",
"publisher": "American Geophysical Union",
"publication": "Journal of Geophysical Research. Planets",
"publication_date": "2022-06",
"series_number": "6",
"volume": "127",
"issue": "6",
"pages": "Art. No. e2021JE007091"
},
{
"id": "authors:bnp1c-vpc91",
"collection": "authors",
"collection_id": "bnp1c-vpc91",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211122-190345294",
"type": "article",
"title": "Resolving Io's Volcanoes from a Mutual Event Observation at the Large Binocular Telescope",
"author": [
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Skrutskie",
"given_name": "Michael",
"orcid": "0000-0001-8671-5901",
"clpid": "Skrutskie-Michael-F"
},
{
"family_name": "Leisenring",
"given_name": "Jarron",
"orcid": "0000-0002-0834-6140",
"clpid": "Leisenring-Jarron-M"
},
{
"family_name": "Davies",
"given_name": "Ashley G.",
"orcid": "0000-0003-1747-8142",
"clpid": "Davies-Ashley-G"
},
{
"family_name": "Conrad",
"given_name": "Al",
"orcid": "0000-0003-2872-0061",
"clpid": "Conrad-Albert"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Resnick",
"given_name": "Aaron",
"clpid": "Resnick-Aaron"
},
{
"family_name": "Bailey",
"given_name": "Vanessa P.",
"orcid": "0000-0002-5407-2806",
"clpid": "Bailey-Vanessa-P"
},
{
"family_name": "Defr\u00e8re",
"given_name": "Denis",
"orcid": "0000-0003-3499-2506",
"clpid": "Defr\u00e8re-Denis"
},
{
"family_name": "Hinz",
"given_name": "Philip",
"orcid": "0000-0002-1954-4564",
"clpid": "Hinz-Philip-M"
},
{
"family_name": "Skemer",
"given_name": "Andrew",
"orcid": "0000-0001-6098-3924",
"clpid": "Skemer-Andrew-J"
},
{
"family_name": "Spalding",
"given_name": "Eckhart",
"orcid": "0000-0003-3819-0076",
"clpid": "Spalding-Eckhart"
},
{
"family_name": "Vaz",
"given_name": "Amali",
"clpid": "Vaz-Amali"
},
{
"family_name": "Veillet",
"given_name": "Christian",
"orcid": "0000-0003-0272-0418",
"clpid": "Veillet-Christian"
},
{
"family_name": "Woodward",
"given_name": "Charles E.",
"orcid": "0000-0001-6567-627X",
"clpid": "Woodward-Charles-E"
}
],
"abstract": "Unraveling the geological processes ongoing at Io's numerous sites of active volcanism requires high spatial resolution to, for example, measure the areal coverage of lava flows or identify the presence of multiple emitting regions within a single volcanic center. In de Kleer et al. (2017) we described observations with the Large Binocular Telescope during an occultation of Io by Europa at \u223c6:17 UT on 2015 March 8 and presented a map of the temperature distribution within Loki Patera derived from these data. Here we present emission maps of three other volcanic centers derived from the same observation: Pillan Patera, Kurdalagon Patera, and the vicinity of Ulgen Patera/PV59/N Lerna Regio. The emission is localized by the light curves and resolved into multiple distinct emitting regions in two of the cases. Both Pillan and Kurdalagon Paterae had undergone eruptions in the months prior to our observations, and the location and intensity of the emission are interpreted in the context of the temporal evolution of these eruptions observed from other facilities. The emission from Kurdalagon Patera is resolved into two distinct emitting regions separated by only a few degrees in latitude that were unresolved by Keck observations from the same month.",
"doi": "10.3847/psj/ac28fe",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2021-12",
"series_number": "6",
"volume": "2",
"issue": "6",
"pages": "Art. No. 227"
},
{
"id": "authors:429nd-21s12",
"collection": "authors",
"collection_id": "429nd-21s12",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210726-213747363",
"type": "article",
"title": "Asteroid 16 Psyche: Shape, Features, and Global Map",
"author": [
{
"family_name": "Shepard",
"given_name": "Michael K.",
"orcid": "0000-0002-8441-2488",
"clpid": "Shepard-Michael-K"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Cambioni",
"given_name": "Saverio",
"orcid": "0000-0001-6294-4523",
"clpid": "Cambioni-Saverio"
},
{
"family_name": "Taylor",
"given_name": "Patrick A.",
"orcid": "0000-0002-2493-943X",
"clpid": "Taylor-Patrick-A"
},
{
"family_name": "Virkki",
"given_name": "Anne K.",
"orcid": "0000-0002-4129-5381",
"clpid": "Virkki-Anne-K"
},
{
"family_name": "R\u00edvera-Valentin",
"given_name": "Edgard G.",
"orcid": "0000-0002-4042-003X",
"clpid": "R\u00edvera-Valentin-Edgard-G"
},
{
"family_name": "Rodriguez Sanchez-Vahamonde",
"given_name": "Carolina",
"orcid": "0000-0002-0390-5054",
"clpid": "Rodriguez-Sanchez-Vahamonde-Carolina"
},
{
"family_name": "Fernanda Zambrano-Marin",
"given_name": "Luisa",
"orcid": "0000-0002-6615-4040",
"clpid": "Fernanda-Zambrano-Marin-Luisa"
},
{
"family_name": "Magri",
"given_name": "Christopher",
"orcid": "0000-0002-2200-4622",
"clpid": "Magri-Christopher"
},
{
"family_name": "Dunham",
"given_name": "David",
"orcid": "0000-0001-7527-4207",
"clpid": "Dunham-David"
},
{
"family_name": "Moore",
"given_name": "John",
"orcid": "0000-0001-8674-4817",
"clpid": "Moore-John"
},
{
"family_name": "Camarca",
"given_name": "Maria",
"orcid": "0000-0003-3887-4080",
"clpid": "Camarca-Maria"
}
],
"abstract": "We develop a shape model of asteroid 16 Psyche using observations acquired in a wide range of wavelengths: Arecibo S-band delay-Doppler imaging, Atacama Large Millimeter Array (ALMA) plane-of-sky imaging, adaptive optics (AO) images from Keck and the Very Large Telescope (VLT), and a recent stellar occultation. Our shape model has dimensions 278 (\u22124/+8 km) \u00d7 238(\u22124/+6 km) \u00d7 171 km (\u22121/+5 km), an effective spherical diameter D_(eff) = 222-1/+4 km, and a spin axis (ecliptic lon, lat) of (36\u00b0, \u22128\u00b0) \u00b1 2\u00b0. We survey all the features previously reported to exist, tentatively identify several new features, and produce a global map of Psyche. Using 30 calibrated radar echoes, we find Psyche's overall radar albedo to be 0.34 \u00b1 0.08 suggesting that the upper meter of regolith has a significant metal (i.e., Fe\u2013Ni) content. We find four regions of enhanced or complex radar albedo, one of which correlates well with a previously identified feature on Psyche, and all of which appear to correlate with patches of relatively high optical albedo. Based on these findings, we cannot rule out a model of Psyche as a remnant core, but our preferred interpretation is that Psyche is a differentiated world with a regolith composition analogous to enstatite or CH/CB chondrites and peppered with localized regions of high metal concentrations. The most credible formation mechanism for these regions is ferrovolcanism as proposed by Johnson et al. (2020).",
"doi": "10.3847/psj/abfdba",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2021-08",
"series_number": "4",
"volume": "2",
"issue": "4",
"pages": "Art. No. 125"
},
{
"id": "authors:c8a6x-mpj82",
"collection": "authors",
"collection_id": "c8a6x-mpj82",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210603-122530519",
"type": "article",
"title": "The Surface of (16) Psyche from Thermal Emission and Polarization Mapping",
"author": [
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Cambioni",
"given_name": "Saverio",
"orcid": "0000-0001-6294-4523",
"clpid": "Cambioni-Saverio"
},
{
"family_name": "Shepard",
"given_name": "Michael",
"orcid": "0000-0002-8441-2488",
"clpid": "Shepard-Michael-K"
}
],
"abstract": "The asteroid (16) Psyche is the largest of the M-type asteroids, which have been hypothesized to be the cores of disrupted planetesimals and the parent bodies of the iron meteorites. While recent evidence has collected against a pure metal composition for Psyche, its spectrum and radar properties remain anomalous. We observed (16) Psyche in thermal emission with the Atacama Large Millimeter/submillimeter Array at a resolution of 30 km over two-thirds of its rotation. The diurnal temperature variations are at the ~10 K level over most of the surface and are best fit by a smooth surface with a thermal inertia of 280 \u00b1 100 J m\u207b\u00b2 K\u207b\u00b9 s^(\u22121/2). We measure a millimeter emissivity of 0.61 \u00b1 0.02, which we interpret via a model that treats the surface as a porous mixture of silicates and metals, where the latter may take the form of iron sulfides/oxides or, alternatively, conducting metallic inclusions. The emissivity indicates a metal content of no less than 20% and potentially much higher, but the polarized emission that should be present for a surface with \u226520% metal content is almost completely absent. This requires a highly scattering surface, which may be due to the presence of reflective metallic inclusions. If such is the case, a consequence is that metal-rich asteroids may produce less polarized emission than metal-poor asteroids, exactly the opposite prediction from standard theory, arising from the dominance of scattering over the bulk material properties.",
"doi": "10.3847/PSJ/ac01ec",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2021-08",
"series_number": "4",
"volume": "2",
"issue": "4",
"pages": "Art. No. 149"
},
{
"id": "authors:gvfnp-c1p45",
"collection": "authors",
"collection_id": "gvfnp-c1p45",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201030-142420466",
"type": "article",
"title": "No evidence of phosphine in the atmosphere of Venus from independent analyses",
"author": [
{
"family_name": "Villanueva",
"given_name": "G. L.",
"orcid": "0000-0002-2662-5776",
"clpid": "Villanueva-Geronimo-L"
},
{
"family_name": "Cordiner",
"given_name": "M.",
"orcid": "0000-0001-8233-2436"
},
{
"family_name": "Irwin",
"given_name": "P. G. J",
"orcid": "0000-0002-6772-384X"
},
{
"family_name": "de Pater",
"given_name": "I.",
"orcid": "0000-0002-4278-3168"
},
{
"family_name": "Butler",
"given_name": "B.",
"orcid": "0000-0002-5344-820X"
},
{
"family_name": "Gurwell",
"given_name": "M.",
"orcid": "0000-0003-0685-3621"
},
{
"family_name": "Milam",
"given_name": "S. N.",
"orcid": "0000-0001-7694-4129"
},
{
"family_name": "Nixon",
"given_name": "C. A.",
"orcid": "0000-0001-9540-9121"
},
{
"family_name": "Luszcz-Cook",
"given_name": "S. H.",
"orcid": "0000-0001-9867-9119"
},
{
"family_name": "Wilson",
"given_name": "C. F.",
"orcid": "0000-0001-5355-1533"
},
{
"family_name": "Kofman",
"given_name": "V.",
"orcid": "0000-0002-5060-1993"
},
{
"family_name": "Liuzzi",
"given_name": "G.",
"orcid": "0000-0003-3638-5750"
},
{
"family_name": "Faggi",
"given_name": "S.",
"orcid": "0000-0003-0194-5615"
},
{
"family_name": "Fauchez",
"given_name": "T. J.",
"orcid": "0000-0002-5967-9631"
},
{
"family_name": "Lippi",
"given_name": "M,",
"orcid": "0000-0001-9185-878X"
},
{
"family_name": "Cosentino",
"given_name": "R.",
"orcid": "0000-0003-3047-615X"
},
{
"family_name": "Thelen",
"given_name": "A. E.",
"orcid": "0000-0002-8178-1042"
},
{
"family_name": "Moullet",
"given_name": "A.",
"orcid": "0000-0002-9820-1032"
},
{
"family_name": "Hartogh",
"given_name": "P.",
"orcid": "0000-0002-9550-6551"
},
{
"family_name": "Molter",
"given_name": "E. M.",
"orcid": "0000-0003-3799-9033"
},
{
"family_name": "Charnley",
"given_name": "S.",
"orcid": "0000-0001-6752-5109"
},
{
"family_name": "Arney",
"given_name": "G. N.",
"orcid": "0000-0001-6285-267X"
},
{
"family_name": "Mandell",
"given_name": "A. M.",
"orcid": "0000-0002-8119-3355"
},
{
"family_name": "Biver",
"given_name": "N.",
"orcid": "0000-0003-2414-5370"
},
{
"family_name": "Vandaele",
"given_name": "A. C.",
"orcid": "0000-0001-8940-9301"
},
{
"family_name": "de Kleer",
"given_name": "K. R.",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Kopparapu",
"given_name": "R.",
"orcid": "0000-0002-5893-2471"
}
],
"abstract": "The detection of phosphine (PH\u2083) in the atmosphere of Venus has been recently reported on the basis of millimetre-wave radio observations and their reanalyses. In this Matters Arising we perform an independent reanalysis, identifying several issues in the interpretation of the spectroscopic data. As a result, we determine sensitive upper limits for PH\u2083 in Venus's atmosphere (>75\u2009km, above the cloud decks) that are discrepant with the findings in refs. 1,2,3.",
"doi": "10.1038/s41550-021-01422-z",
"issn": "2397-3366",
"publisher": "Nature Publishing Group",
"publication": "Nature Astronomy",
"publication_date": "2021-07",
"series_number": "7",
"volume": "5",
"issue": "7",
"pages": "631-635"
},
{
"id": "authors:efr3n-mtx05",
"collection": "authors",
"collection_id": "efr3n-mtx05",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210820-235732803",
"type": "article",
"title": "A 2020 Observational Perspective of Io",
"author": [
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Keane",
"given_name": "James T.",
"orcid": "0000-0002-4803-5793",
"clpid": "Keane-James-T"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Davies",
"given_name": "Ashley Gerard",
"orcid": "0000-0003-1747-8142",
"clpid": "Davies-Ashley-Gerard"
}
],
"abstract": "Jupiter's Galilean satellite Io is one of the most remarkable objects in our Solar System. The tidal heating Io undergoes through its orbital resonance with Europa and Ganymede has resulted in a body rich in active silicate volcanism. Over the past decades, Io has been observed from ground-based and Earth-orbiting telescopes and by several spacecraft. In this review we summarize the progress made toward our understanding of the physical and chemical processes related to Io and its environment since the Galileo era. Io science has been revolutionized by the use of adaptive optics techniques on large, 8- to 10-m telescopes. The resultant ever-increasing database, mapping the size, style, and spatial distribution of Io's diverse volcanoes, has improved our understanding of Io's interior structure, its likely composition, and the tidal heating process. Additionally, new observations of Io's atmosphere obtained with these large optical/infrared telescopes and the Atacama Large Millimeter/submillimeter Array reveal the presence of volcanic plumes, the (at times) near-collapse of Io's atmosphere during eclipse, and the interactions of plumes with the sublimation atmosphere.",
"doi": "10.1146/annurev-earth-082420-095244",
"issn": "0084-6597",
"publisher": "Annual Reviews",
"publication": "Annual Review of Earth and Planetary Sciences",
"publication_date": "2021-05",
"volume": "49",
"pages": "643-678"
},
{
"id": "authors:ny5r7-cpq74",
"collection": "authors",
"collection_id": "ny5r7-cpq74",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210122-151827531",
"type": "article",
"title": "Ganymede's Surface Properties from Millimeter and Infrared Thermal Emission",
"author": [
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Butler",
"given_name": "Bryan",
"orcid": "0000-0002-5344-820X",
"clpid": "Butler-Bryan-J"
},
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-Imke"
},
{
"family_name": "Gurwell",
"given_name": "Mark A.",
"orcid": "0000-0003-0685-3621",
"clpid": "Gurwell-Mark-A"
},
{
"family_name": "Moullet",
"given_name": "Arielle",
"orcid": "0000-0002-9820-1032",
"clpid": "Moullet-Arielle"
},
{
"family_name": "Trumbo",
"given_name": "Samantha",
"orcid": "0000-0002-0767-8901",
"clpid": "Trumbo-Samantha-K"
},
{
"family_name": "Spencer",
"given_name": "John",
"clpid": "Spencer-John-R"
}
],
"abstract": "We present thermal observations of Ganymede from the Atacama Large Millimeter Array (ALMA) in 2016\u20132019 at a spatial resolution of 300\u2013900 km (0.\"1\u20130.\"2 angular resolution) and frequencies of 97.5, 233, and 343.5 GHz (wavelengths of 3, 1.3, and 0.87 mm); the observations collectively covered all Ganymede longitudes. We determine the global thermophysical properties using a thermal model that considers subsurface emission and depth- and temperature-dependent thermophysical and dielectric properties, in combination with a retrieval algorithm. The data are sensitive to emission from the upper ~0.5 m of the surface, and we find a millimeter emissivity of 0.75\u20130.78 and (sub)surface porosities of 10%\u201340%, corresponding to effective thermal inertias of 400\u2013800 J m\u207b\u00b2 K\u207b\u00b9 s^(\u22121/2). Combined with past infrared results, as well as modeling presented here of a previously unpublished night-time infrared observation from Galileo's photopolarimeter\u2013radiometer instrument, the multiwavelength constraints are consistent with a compaction profile whereby the porosity drops from ~85% at the surface to 10\u207a\u00b3\u2070\u208b\u2081\u2080% at depth over a compaction length scale of tens of centimeters. We present maps of temperature residuals from the best-fit global models, which indicate localized variations in thermal surface properties at some (but not all) dark terrains and at impact craters, which appear 5\u20138 K colder than the model. Equatorial regions are warmer than predicted by the model, in particular near the centers of the leading and trailing hemispheres, while the midlatitudes (~30\u00b0\u201360\u00b0) are generally colder than predicted; these trends are suggestive of an exogenic origin.",
"doi": "10.3847/psj/abcbf4",
"issn": "2632-3338",
"publisher": "American Astronomical Society",
"publication": "Planetary Science Journal",
"publication_date": "2021-02",
"series_number": "1",
"volume": "2",
"issue": "1",
"pages": "Art. No. 5"
},
{
"id": "authors:jf3cr-h0t92",
"collection": "authors",
"collection_id": "jf3cr-h0t92",
"cite_using_url": "https://authors.library.caltech.edu/records/jf3cr-h0t92",
"type": "monograph",
"title": "ALMA Observations of Io Going into and Coming out of Eclipse",
"author": [
{
"family_name": "de Pater",
"given_name": "Imke",
"orcid": "0000-0002-4278-3168",
"clpid": "de-Pater-I"
},
{
"family_name": "Luszcz-Cook",
"given_name": "Statia",
"orcid": "0000-0001-9867-9119",
"clpid": "Luszcz-Cook-S"
},
{
"family_name": "Rojo",
"given_name": "Patricio",
"orcid": "0000-0002-1607-6443",
"clpid": "Rojo-Patricio"
},
{
"family_name": "Redwing",
"given_name": "Erin",
"orcid": "0000-0002-5595-3808",
"clpid": "Redwing-E"
},
{
"family_name": "de Kleer",
"given_name": "Katherine",
"orcid": "0000-0002-9068-3428",
"clpid": "de-Kleer-K-R"
},
{
"family_name": "Moullet",
"given_name": "Arielle",
"orcid": "0000-0002-9820-1032",
"clpid": "Moullet-A"
}
],
"abstract": "\n
We present 1 mm observations constructed from Atacama Large (sub)Millimeter Array (ALMA) data of SO2, SO, and KCl when Io went from sunlight into eclipse (2018 March 20) and vice versa (2018 September 2 and 11). There is clear evidence of volcanic plumes on March 20 and September 2. The plumes distort the line profiles, causing high-velocity (\u2273500 m s−1) wings and red-/blueshifted shoulders in the line profiles. During eclipse ingress, the SO2 flux density dropped exponentially, and the atmosphere re-formed in a linear fashion when reemerging in sunlight, with a “post-eclipse brightening” after ∼10 minutes. While both the in-eclipse decrease and in-sunlight increase in SO was more gradual than for SO2, the fact that SO decreased at all is evidence that self-reactions at the surface are important and fast, and that in-sunlight photolysis of SO2 is the dominant source of SO. Disk-integrated SO2 in-sunlight flux densities are ∼2–3 times higher than in eclipse, indicative of a roughly 30%–50% contribution from volcanic sources to the atmosphere. Typical column densities and temperatures are N ≈ (1.5 ± 0.3) × 1016 cm−2 and T ≈ 220–320 K both in sunlight and in eclipse, while the fractional coverage of the gas is two to three times lower in eclipse than in sunlight. The low-level SO2 emissions present during eclipse may be sourced by stealth volcanism or be evidence of a layer of noncondensible gases preventing complete collapse of the SO2 atmosphere. The melt in magma chambers at different volcanoes must differ in composition to explain the absence of SO and SO2, but simultaneous presence of KCl over Ulgen Patera.
\n