Pulsating white dwarfs as astrophysical tools

Abstract

Abstract. The study of pulsating white dwarfs is a scientifically productive exercise as their measured pulsation characteristics yield both unique data on their interiors and also shed light on more general astrophysical questions. The modelling process is simplified due to their assumed chemically homogeneous and layered structures. As well as being archaeological remnants of their nuclear burning progenitors, white dwarfs are cosmic laboratories that can provide some observational constraints on theories of matter in regions of phase space that are unattainable in laboratories on Earth. The hotter white dwarfs should feature neutrino production by several unusual weak interaction processes, while their cooler cousins should exhibit core crystallization. White dwarf pulsators are very stable in period (if not always in amplitude) and suitable objects can be used as sensitive orbiting clocks in a search for stellar companions, including those of planetary size. Finally, the ensemble of cooling white dwarfs can be used as an independent cosmic chronometer over very long timescales if the cooling curve is properly calibrated. The pulsators make important contributions in this regard.