The dispersion of period spacing for DAV stars

TL;DR

This study investigates how hydrogen atmosphere thickness affects period spacing dispersion in DAV stars, revealing that thinner atmospheres increase dispersion and identifying modes partly trapped in the core.

Contribution

It introduces models with realistic core compositions from MESA and analyzes the impact of hydrogen layer thickness on period spacing dispersion in DAV stars.

Findings

Thinner hydrogen atmospheres lead to more dispersive period spacings.

Modes partly trapped in the C/O core are identified in DAV star models.

KUV03442+0719 may be the first observed star with modes partly trapped in the core.

Abstract

Three groups of DAV star models are evolved with time-dependent element diffusion by \texttt{WDEC}. The core compositions of these models are directly from white dwarf models evolved by \texttt{MESA}, which are results of thermonuclear burning. Based on these DAV star models, we try to study the dispersion of period spacing. The thickness of hydrogen atmosphere can seriously affect the deviation degree of minimal period spacings. The minimal period spacings dominate the dispersion of period spacing. The thinner the hydrogen atmosphere, basically, the more dispersive the period spacing. Standard deviations are used to analyze the dispersion of period spacing. Studying the dispersion of period spacing on a DAV star KUV03442+0719 preliminarily, we suggest that log($M_{\rm H}/M_{*}$) is from -8.5 to -5.5. In addition, modes partly trapped in C/O core are found based on those DAV star models. The identified modes and average period spacings indicate that KUV03442+0719 may be the first star to 'observe' modes partly trapped in C/O core.