Asteroseismology of DAV star EC14012-1446, mode identification and model fittings

TL;DR

This study analyzes the pulsation modes of the DAV star EC14012-1446 through extensive observations, mode identification, and model fitting, revealing detailed internal structure and mode trapping phenomena.

Contribution

It provides a comprehensive mode identification and best-fitting white dwarf model using combined observational data and advanced modeling techniques, including core composition from MESA.

Findings

Identified 34 independent pulsation frequencies and modes.

Determined a best-fitting model with specific stellar parameters.

Detected mode trapping in the hydrogen envelope.

Abstract

EC14012-1446 was observed by Handler et al. in April 2004, June 2004, May 2005, and April 2007, and by Provencal et al. in 2008. We review the observations together and obtain 34 independent frequencies. According to the frequency splitting and the asymptotic period spacing law, we identify 6 $l$=1 modes, 4 $l$=2 modes, 5 $l$=3 modes, 10 $l$=1 or 2 modes. Grids of white dwarf models are generated by WDEC with H, He, C, O diffusion in a four-parameter space. The core compositions are directly from white dwarf models generated by MESA. The best-fitting model has $M_{*}$=0.710\,$M_{\odot}$, $T_{\rm eff}$=12200\,K, log($M_{\rm He}/M_{*}$)=-2.5, log($M_{\rm H}/M_{*}$)=-7.0, log\,$g$=8.261, and $\phi$=3.185\,s. There are 4, 2, and 1 modes identified as trapped in H envelope for observed $l$=1, 2, and 3 modes, respectively. Trapped modes jump the queue of uniform period spacing.