Asteroseismology of the ZZ Ceti star KUV 08368+4026

TL;DR

This study uses extensive observational data and theoretical modeling to analyze the internal structure and rotation of the ZZ Ceti star KUV 08368+4026 through asteroseismology, revealing its pulsation modes and stellar parameters.

Contribution

It provides detailed asteroseismic analysis of KUV 08368+4026, including mode identification, rotation period, and stellar model fitting, advancing understanding of ZZ Ceti white dwarfs.

Findings

Identified 30 pulsation frequencies including multiplets.

Determined the star's rotation period as approximately 5.52 days.

Derived stellar parameters: mass, luminosity, and hydrogen layer mass.

Abstract

Asteroseismology is a unique tool to explore the internal structure of stars through both observational and theoretical research. The internal structure of pulsating hydrogen shell white dwarfs (ZZ Ceti stars) detected by asteroseismology is regarded as the representative of all DA white dwarfs. Observations for KUV~08368+4026, which locates in the middle of the ZZ Ceti instability strip, have been carried out in 1999 and from 2009 to 2012 with either single-site runs or multisite campaigns. Time-series photometric data of about 300 hours were collected in total. Through data reduction and analysis, 30 frequencies were extracted, including four triplets, two doublets, one single mode and further signals. The independent modes are identified as either l=1 or l=2 modes. Hence, a rotation period of $5.52\pm 0.22$ days was deduced from the period spacing in the multiplets. Theoretical static models were built and a best fit model for KUV~08368+4026 was obtained with $0.692\pm0.002$ solar mass, $(2.92\pm0.02)\times 10^{-3}$ solar luminosity and the hydrogen mass fraction of $10^{-4}$ stellar mass.