Excitation and Damping of Solar and Stellar Oscillations

Abstract

Variable stars can be broadly classified into two categories: (a) High amplitude pulsators like Cepheids and RR Lyrae variables, (b) Low amplitude pulsators like Sun and Sun-like stars. The study of stellar pulsations has opened the possibility of using the oscillatory modes to probe the internal structure and dynamics of these stars. The cause of pulsational instability for a majority of stars is the partial ionisation of the abundant elements present in the envelope of the stars, while some instabilities are driven by the transfer of momentum from the medium to the oscillating elements. Various mechanisms responsible for exciting and limiting the solar and stellar oscillations are discussed.