Ground based observation of ZZ Ceti stars and the discovery of four new variables

TL;DR

This study conducts ground-based photometry of white dwarf stars, discovering four new ZZ Ceti variables, analyzing their pulsation properties, and comparing asteroseismological models with other observational data.

Contribution

It reports the discovery of four new ZZ Ceti stars and provides detailed asteroseismological analysis, expanding understanding of white dwarf pulsations.

Findings

Four new ZZ Ceti variables discovered

Confirmed period stability in known ZZ Ceti stars

Asteroseismological models align with Gaia data

Abstract

We perform ground based photometric observations of 22 DA white dwarf stars, 10 already known ZZ Cetis and 12 candidates with atmospheric parameters inside the classical instability strip. We report on the discovery of four new variable DA white dwarf stars. Two objects are near the middle of the instability strip, SDSS J082804.63+094956.6 and SDSS J094929.09+101918.8, and two red edge pulsators, GD 195 and L495-82. In addition, we classified four objects as possible variables, since evidence of variability was detected in the light curve, but the S/N was not sufficient to establish a definite detection. Follow-up observations were performed for 10 know ZZ Ceti stars to verify period stability and search for new periodicities. For each confirmed variable, we perform a detailed asteroseismological fit and compare the structural parameters obtained from the best fit models with those obtained from spectroscopy and photometry from Gaia. Finally we present a study of the asteroseismological properties of a sample of 91 ZZ Ceti stars.