White dwarf evolution in real time: What pulsating white dwarfs teach us about stellar evolution

The frontier of stellar evolution represented by the white dwarfs is being pushed back thanks to observational mapping of the pulsation properties of the WDVs over the past 20 years; it is worthwhile to note that the most important tools in all this work have been modest 1-meter class telescopes. Using the observed pulsation spectra of the WDVs, pulsation theory has been able to determine some important quantities describing white dwarfs, such as rotation velocities and total masses. The evolutionary time scale for hot white dwarfs has been measured; it is just a matter of time before the more gradual changes in cooler white dwarfs are also detected. With a little additional work on both observational and theoretical sides, we may soon measure moderate magnetic fields in WDVs. We will also soon be able to quantitatively determine the compositional structure of their outer layers as modelling progresses. Even the lack of observed pulsations in the hottest white dwarfs is leading to re-evaluation of models of their structure. All of this success is rooted in the analysis of the basic pulsation spectra; the rich observed variations on this linear theme promise to provide additional detailed information on white dwarf structure and evolution. The WDVs are garden variety white dwarfs that have simply been caught in the act of pulsation; they are currently in one of the relatively brief phases of their evolution in which they are vibrationally unstable. By studying the properties of the pulsators, then, one is sampling the properties of all white Dwarfs