On the Excitation of Oscillations of the Sun (Numerical Models)

Abstract

AbstractNumerical solutions of the general time-dependent gas-dynamical equations in linear adiabatic approximation are given for initial conditions imitating: (a) a central perturbation, (b) a boundary perturbation (in the convective envelope), and (c) a ‘shrinking’ of the Sun as a whole. For a variety of models of the Sun it is found that at the surface the radial component vr of velocity is much greater than the tangential component vt, and that the period T of stationary oscillations does not exceed 131m. The appearance at the surface of a g mode with period 160m is found to be improbable.With the initial conditions adopted, a propagating wave is produced which is reflected successively from the centre to the periphery and back, producing 5-min oscillations at the surface of the Sun. Expansion of this wave into separate modes leads to a power spectrum qualitatively similar to that observed.