The rate of period change in DAV stars

Abstract

Grids of DAV star models are evolved by \texttt{WDEC}, taking the element diffusion effect into account. The grid parameters are hydrogen mass log($M_H/M_{\ast }$), helium mass log($M_{He}/M_{\ast }$), stellar mass $M_{\ast }$, and effective temperature $T_{\mathrm{eff}}$ for DAV stars. The core compositions are from white dwarf models evolved by \texttt{MESA}. Therefore, those DAV star models evolved by \texttt{WDEC} have historically viable core compositions. Based on those DAV star models, we studied the rate of period change ($\dot{P}(k)$) for different values of H, He, $M_{\ast }$, and $T_{\mathrm{eff}}$. The results are consistent with previous work. Two DAV stars G117-B15A and R548 have been observed around forty years. The rates of period change of two large-amplitude modes were obtained through O-C method. We did asteroseismological study on the two DAV stars and then obtained a best-fitting model for each star. Based on the two best-fitting models, the mode identifications ($l$, $k$) of the observed modes for G117-B15A and R548 are consistent with previous work. Both the observed modes and the observed $\dot{P}$s can be fitted by calculated ones. The results indicate that our method of evolving DAV star models is feasible.

arXiv comment20pages, 12 figures, 6 tables, accepted by RAA on 3/18, 2017

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• Probing the dark matter-electron interactions via hydrogen-atmosphere pulsating white dwarfs
• Asteroseismology of the DOV star PG 1159-035