Asteroseismology of DAV white dwarf stars and G29-38

TL;DR

This paper discusses the methods and challenges of using asteroseismology to study DAV white dwarf stars, focusing on mode identification, model fitting, and the specific case of G29-38, highlighting the need for further methodological development.

Contribution

It provides a detailed analysis of period fitting methods and mode identification strategies for DAV stars, especially G29-38, and discusses their implications for understanding white dwarf inner structures.

Findings

Assuming all observed modes are l=1 leads to large model fitting errors.

Including l=2 modes reduces fitting errors but introduces mode identification ambiguities.

Current models do not fully align with previous atmospheric results for G29-38.

Abstract

Asteroseismology is a powerful tool to detect the inner structure of stars. It is also widely used to study white dwarfs. In this paper, we discuss the asteroseismology work of DAV stars. The detailed period to period fitting method is fully discussed, including the reliability to detect the inner structure of DAV stars. If we assume that all observed modes of some DAV star are the $l$ = 1 ones, the errors of model fitting will be always great. If we assume that the observed modes are composed of $l$ = 1 and 2 modes, the errors of model fitting will be small. However, there will be modes identified as $l$ = 2 without quintuplets observed. G29-38 has been observed spectroscopically and photometrically for many years. Thompson et al. (2008) made $l$ identifications for the star through limb darkening effect. With eleven known $l$ modes, we also do the asteroseismology work for G29-38, which reduces the blind $l$ fittings and is a fair choice. Unfortunately, our two best-fitting models are not in line with the previous atmospheric results. Based on factors of only a few modes observed, stability and identification of eigenmodes, identification of spherical degrees, construction of physical and realistic models and so on, detecting the inner structure of DAV stars by asteroseismology needs further development.