Theory of solar and stellar oscillations - I and II - ABSTRACT

Oscillations of many stars, including the Sun, have sufficiently small amplitudes that they can be treated as small perturbations around an equilibrium structure. This makes their frequencies rather clean diagnostics of the properties of stellar interiors, and hence greatly simplifies helioseismic and asteroseismic analyses. Equally importantly, many of the observed modes, including those seen in the Sun, can be approximated by asymptotic expressions based on the properties of simple acoustic or internal gravity waves. This provides a deep understanding of the diagnostic potential of the modes and forms the basis for simple asymptotic inversion techniques.

The origin of the oscillations in the Sun and sun-like stars is believed to be stochastic excitation by the vigorous near-surface convection in these stars. Models of this process are in reasonable accord with the observed properties of the modes.

Some preliminary reading

• Christensen-Dalsgaard, J., 2004, Lecture Notes on Stellar Oscillations, fifth edition, in particular Chapters 3 - 8 and 10.
• Christensen-Dalsgaard, J., 2004. `Physics of solar-like oscillations'. Solar Phys., 220, 137 - 168. A preprint is available here as PDF file and as a gzipped PS file.
• Christensen-Dalsgaard, J., 2002. `Helioseismology'. Rev. Mod. Phys., 74, 1073 - 1129. The paper is available here as PDF file.
• A gentle introduction to helio- and asteroseismology.