ASTEROSEISMOLOGY OF WHITE DWARFS AND SUBDWARF B STARS

摘要

The technical characteristics of the Eddington mission allow to obtain crucial results in the field of white dwarf (WD) and subdwarf B (sdB) seismology. The huge improvement of the Eddington data, with respect to present ground-based multi-site campaigns, relies on many factors: longer runs (from 2-3 weeks to months/years), much cleaner spectral windows (coverage of 90% or more), higher photometric accuracy, better homogeneity of the data set. For all these reasons we can expect that Eddington observations on WD/sdB pulsators would have an important impact on many of the following topics: pulsational models (better adiabatic and nonadiabatic models and more accurate/robust seismic results), WD/sdB structure (e.g. stellar mass, WD transition zones, C/O ratio in WD cores and ~(12)C(α, γ)~(16)O reaction rate), WD/sdB evolution (e.g. previous evolution of the sdB stars, still unclear; P and evolutionary time scales for the instability strips), WD cooling (ratio of crystallized matter in the core) and WD luminosity function.