Asteroseismological Study On DA Pulsating Variable Stars

Firstly, this paper introduces brie?y white dwarfs, pulsating white dwarfs, the theory of star pulsation, asteroseismology on white dwarfs, white dwarf evolution program, and white dwarf pulsation program. Secondly, I do the asteroseismology work and compare to spectroscopy work for three DAV stars, namely G29-38, HS0507+0434B, and EC14012-1446. At last, I want to combine the asteroseismology work with the spectroscopy work for GD154 and hope to obtain a reliable result in the next work.According to the limb darkening e?ect produced by geometry position of di?erent spherical harmonic degrees, Thompson made mode identi?cations for G29-38 in 2008. Mesh models are evolved by WDEC, adopting di?usion equilibrium pro?les between C/He and He/H. The core compositions are 20% carbon on the center of C/O core, 60% carbon on the surface of C/O core, and linear pro?le between them. The asteroseismology results are consistent with the spectroscopy results of Xu et al. in 2014 but dis-consistent with other spectroscopy results.Fu et al. made new mode identi?cations on HS0507+0434B in 2013 according to their WET observations. Six triplets are identi?ed with equally spaced frequency splitting values. Mesh white dwarfs are evolved by WDEC. The core compositions are from linear ?ttings to carbon pro?le of a white dwarf model from MESA. The asteroseismology results are close to the spectroscopy results of Fontaine et al. in 2003 and Koester et al. in 2009, but far from the spectroscopy results of Gianninas et al. in 2011.Combining the independent frequencies identi?ed by Handler et al. in 2008 and by Provencal et al. in 2012, I make new mode identi?cations on EC14012-1446. According to the frequency splitting law and the equally spaced period spacing law, 6 l = 1,4 l = 2,5 l = 3,and 10 l = 1 or 2 modes are identi?ed.The total stellar masses of white dwarfs evolved by MESA should be matched to the total stellar masses of white dwarfs required by WDEC. Taking the element di?usion into account, I do not adopt the di?usion equilibrium pro?les directlywhen evolving white dwarfs in WDEC. The asteroseismology results are a little larger than the previous spectroscopy results.Reliable mode identi?cations and physical model evolutions are required for asteroseismology work on white dwarfs. Combining asteroseismology work and spectroscopy work is an e?ective and feasible method to study white dwarfs.