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

Abstract

AbstractProgress 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 p1 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).