Asteroseismology of ZZ Ceti stars with fully evolutionary white dwarf
models: I. The impact of the uncertainties from prior evolution on the period
spectrum
ZZ Ceti stars are pulsating white dwarfs with a carbon-oxygen core build up
during the core helium burning and thermally pulsing Asymptotic Giant Branch
phases. Through the interpretation of their pulsation periods by means of
asteroseismology, details about their origin and evolution can be inferred. The
whole pulsation spectrum exhibited by ZZ Ceti stars strongly depends on the
inner chemical structure. At present, there are several processes affecting the
chemical profiles that are still not accurately determined. We present a study
of the impact of the current uncertainties of the white dwarf formation and
evolution on the expected pulsation properties of ZZ Ceti stars. Our analysis
is based on a set of carbon-oxygen core white dwarf models with masses 0.548
and 0.837 M_{\sun} derived from full evolutionary computations from the ZAMS
to the ZZ Ceti domain. We have considered models in which we varied the number
of thermal pulses, the amount of overshooting, and the
12C(α,γ)16O reaction rate within their uncertainties. We
explore the impact of these major uncertainties in prior evolution on the
chemical structure and the expected pulsation spectrum. We find that these
uncertainties yield significant changes in the g-mode pulsation periods. We
conclude that the uncertainties in the white dwarf progenitor evolution should
be be taken into account in detailed asterseismological analysis of these
pulsating stars.Comment: 7 pages, 8 figures. To be published in Astronomy and Astrophysic