THE POTENTIAL FOR ASTEROSEISMOLOGY OF DB WHITE-DWARF STARS

We present the results of a parametric survey of evolutionary models of compositionally stratified white dwarfs with helium surface layers (DB white dwarfs). Because white dwarfs are the most common final end state of stellar evolution, determining their internal structure will offer us many clues about stellar evolution and the physics of matter under extreme conditions. As a first step towards determining the intcrnal structure of DB white dwarf stars, we provide a comprehensive set of theoretical g-mode pulsation periods for comparison to observations of pulsating DB white dwarfs. We show how we can use the distribution of pulsation periods observed in DB white dwarfs to determine their total stellar mass, their helium surface layer masses, and the extent of their helium/carbon and carbon/oxygen transition zones. Rates of period change for the pulsation modes will tell us about the core composition of DB white dwarfs. With these tools, we are in a position to determine the structure of the pulsating DB white dwarfs, once the requisite observations become available.