From Helioseismology to Asteroseismology: Some Recent Developments

While variable stars have been observed and analyzed for more than two centuries, the study of solar-type oscillations is new and presently blooming. In this introductory presentation, we first recall the general basis for asteroseismology, the so-called “asymptotic theory” of stellar oscillations and discuss important deviations from this theory. Then we focus on solar-type stars and give two examples for which it was possible to derive precise stellar parameters from seismology, specially the helium abundance, which is not obtained in these stars from spectroscopy alone. The potentiality of asteroseismology for a better knowledge of stellar structure and evolution is huge, and many new results are expected in the near future.