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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenThu, 30 Nov 2023 18:11:36 +0000Fine Structure in Solar Oscillation Spectra
https://resolver.caltech.edu/CaltechAUTHORS:20201008-112317661
Authors: Libbrecht, Ken G.
Year: 1987
DOI: 10.1007/978-94-009-3903-5_8
I discuss here two aspects of helioseismology which rely on precise measurements of the relative frequencies of solar oscillation modes: rotational and magnetic mode splittings, and solar cycle changes in the mode frequencies. Recent data are presented, along with speculation into the future of the measurements.https://authors.library.caltech.edu/records/tgtbz-s7550Observations of solar cycle variations in solar p-mode frequencies and splittings
https://resolver.caltech.edu/CaltechAUTHORS:20201008-112317386
Authors: Libbrecht, K. G.; Woodard, M. F.
Year: 1990
DOI: 10.1007/3-540-53091-6_75
We discuss here two sets of helioseismology data acquired at Big Bear Solar Observatory during the summers of 1986 and 1988. Each data set consists of roughly 60,000 fulldisk Doppler images of the sun, accumulated over a four-month time span. These data clearly show that solar p-mode frequencies change with time, and that the measured frequency shifts Δv = v₈₈ - v₈₆ depend strongly on frequency and only weakly on ℓ for 5 ≤ ℓ ≤ 60. The frequency dependence is well described by Δv ∞ M⁻¹(v), where M(v) is the mode mass for low-ℓ modes. Such a frequency dependence is expected if the effective sound speed perturbation is located predominantly near the solar surface. It should be possible to invert the frequency shift measurements to determine some aspects of the structure of solar activity as a function of depth. The data also show that the even-index splitting coefficients depend strongly on frequency, again being well described by α_(2j) (v) ∞ M⁻¹(v). This functional form is expected if the sound speed perturbation responsible for Δv is localized in solar latitude. Latitude inversions of the time-dependent splitting and Δv measurements show that the perturbation is strongest in the active latitudes, but includes a weak polar component.https://authors.library.caltech.edu/records/2xm3a-yg524Snow Crystal Structure
https://resolver.caltech.edu/CaltechAUTHORS:20201008-112317470
Authors: Libbrecht, Kenneth G.
Year: 2011
DOI: 10.1007/978-90-481-2642-2_662
Snow crystals, also called snowflakes, are single crystals of ice that grow from water vapor. They form in copious numbers in the atmosphere and are well known for their elaborate, symmetrical patterns. Figure 1 shows several examples of natural snow crystals.https://authors.library.caltech.edu/records/a6ncs-ntm83