GD 244: asteroseismology of a pulsator in the middle of the ZZ Ceti instability strip

TL;DR

This study conducts preliminary asteroseismological analysis of the ZZ Ceti star GD 244 using observed pulsation modes and stellar models, revealing its mass range, hydrogen layer thickness, and internal composition.

Contribution

It introduces a new asteroseismological analysis of GD 244 with model fitting based on observed pulsations and stellar evolution models, providing insights into its internal structure.

Findings

Star's mass between 0.61 and 0.74 solar masses.

Hydrogen layer masses of approximately 10^{-5} or 10^{-6} solar masses.

Star's mass likely below 0.68 solar masses with less than 60% oxygen in the core.

Abstract

We present our preliminary results on the asteroseismological investigations of the ZZ Ceti star GD 244. We used literature values of the effective temperature and surface gravity and utilized the White Dwarf Evolution Code of Bischoff-Kim, Montgomery and Winget (2008, ApJ, 675, 1512) to build our model grid for the seismological analysis. Five observed pulsational modes published up to now were used to find acceptable model solutions. We found that the best model fits have masses between 0.61 and 0.74 M_solar and constitute two groups with hydrogen layer masses of either ~10^{-5} or 10^{-6} M_solar. Based on a statistical analysis of a larger sample of possible model solutions, we assume that the mass of the star is below ~0.68 M_solar and the oxygen content in the centre is less than 60 percent.