Mode Identification Revisit and Asteroseismology of the DAV Star TIC 231277791

Abstract White dwarfs (WDs) are the final stage for most low and intermediate mass stars, which play an important role in understanding stellar evolution and galactic history. Here we performed an asteroseismological analysis on TIC 231277791 based on 10 independent modes reported by Romero et al. Two groups of modes were identified with frequency splitting: mode identification_1 with one l = 1, m = 0 mode, two l = 2, m = 0 modes, and three l = 1 or 2, m = 0 modes, and mode identification_2 with one l = 1, m = 0 mode, three l = 2, m = 0 modes, and one l = 1 or 2, m = 0 mode. The rotation period is derived to be 41.64 ± 2.73 hr for TIC 231277791. We established a large sample (7,558,272) of DAV star models using the White Dwarf Evolution Code ( WDEC ; 2018, v16), resulting of optimal models with model_1 (mode identification_1): M * = 0.570 ± 0.005 M ⊙ , T eff = 11300 ± 10 K, −log( M H / M * ) = 9.15 ± 0.01, −log( M He / M * ) = 4.94 ± 0.01, and σ rms = 0.06 s, and model_2 (mode identification_2): M * = 0.720 ± 0.005 M ⊙ , T eff = 1910 ± 10 K, −log( M H / M * ) = 6.11 ± 0.01, −log( M He / M * ) = 3.09 ± 0.01, and σ rms = 0.04 s. The central oxygen abundances are 0.71 (optimal model_1) and 0.72 (optimal model_2), respectively, which are consistent with the results of stellar structure and evolution theory.