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Sunspot Seismology: The Interaction of Solar p-Modes with a Sunspot

Published online by Cambridge University Press:  12 April 2016

John H. Thomas
John H. Thomas*
Affiliation:
Department of Mechanical Engineering, Department of Physics and Astronomy, and C. E. K. Mees Observatory, University of Rochester, Rochester, NY 14627

Abstract

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Progress in sunspot seismology is briefly reviewed. New observations of the absorption of p-modes by a sunspot (Bogdan, Brown, Lites, and Thomas 1993) show that the absorption coefficient (averaged over frequency and azimuthal order) increases with horizontal wavenumber to a maximum near k = 0.9 Mm−1 and then decreases monotonically to zero at about k = 1.5 Mm−1. The absorption along individual p-mode ridges shows a sinusoidal-like modulation, which may be an important feature for comparison with theory. Results for the quiet Sun show no net absorption, but do show apparent emission along p 1 over the same range of k where the sunspot shows its greatest absorption. This behavior, and the overall decrease in absorption at higher wavenumbers, can be explained as an effect of the decreasing lifetime of p-modes with increasing wavenumber k (increasing mode degree l).

Information

Type
Session 9. Convections and Oscillation in Active Regions
Information
International Astronomical Union Colloquium , Volume 141: The Magnetic and Velocity Fields of Solar Active Regions , 1993 , pp. 513 - 521
Copyright
Copyright © Astronomical Society of the Pacific 1993

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