Asteroseismology of the DAV star KUV 08368+4026

Abstract

As a DAV star, KUV 08368+4026 was observed by Li et al. in 2009 February, 2009 December, 2010 January, and 2012 February. They extracted 30 frequencies from the reported 300 h observation data and identified 17 independent modes. Based on the frequency splitting relationship, 6 l = 1 modes and 1 l = 2 mode are identified. The seven identified modes are reliable and can be used to constrain fitting models. A large sample (7,558,272) DAV star models were established using White Dwarf Evolution Code (WDEC; 2018 version). The theoretical modes are calculated and used to fit the observed modes in order to obtain a best-fitting model. The best-fitting model has an average fitting error of σ_RMS = 0.71 s. The best-fitting model parameters are M_* = 0.685 ± 0.005 M_⊙, T_eff = 11820 ± 40 K, log(M_He/M_*) = - 5.00 ± 0.01, and, log(M_H/M_*) = - 6.90 ± 0.01. The stellar mass M_* and effective temperature T_eff of the best-fitting model are basically consistent with the results of the spectroscopy. The mass of the He layer is thinner than the results obtained from previous asteroseismic models. The best-fitting model has a small Carbon/Oxygen central core with an oxygen abundance of X_O = 0.76. The asteroseismological distance calculated using the luminosity of our best-fitting model is basically consistent with that of the Kiso Schmidt ultraviolet excess survey.