Physical Society Colloquium

Asteroseismology has become a fashionable subfield of astrophysics in recent years. It is basically a technique that allows one to probe the internal structure of stars and infer their global properties such as mass, radius, and surface temperature. The actual "probes" are the normal modes of oscillation that are excited during particular phases of the evolution of a star. It is during such phases that one can observe and study the excited modes which manifest themselves in terms of luminosity variations. Theoretical calculations have led us to postulate three years ago the existence of a new class of oscillating stars, that of the pulsating hot B subdwarfs (sdB), a family of evolved stars that are the parents of a fraction of the white dwarf stars. This prediction was confirmed at the telescope, and we now know of 15 pulsating sdB stars. We will focus, in this talk, on some very recent observational and theoretical advances in our understanding of these fascinating objects. These include the very first detailed mode identification and determination of stellar parameters on the basis of asteroseismological arguments for a pulsator of this kind.

Friday, November 26th 1999, 15:30
Ernest Rutherford Physics Building, Keys Auditorium (room 112)