EPIC 228782059: Asteroseismology of What Could Be the Coolest Pulsating Helium-atmosphere White Dwarf (DBV) Known
EPIC 228782059: Asteroseismology of What Could Be the Coolest Pulsating Helium-atmosphere White Dwarf (DBV) Known
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EPIC 228782059：已知最冷脉动氦大气白矮星 (DBV) 的星震学
DOI：
10.3847/1538-4357/ac22fd
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
S. Charpinet
中科院分区：
文献类型：
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作者：
R. M. Duan;Weikai Zong;J.-N. Fu;Y. H. Chen;J. J. Hermes;Zachary P. V;erbosch;X. Y. Ma;S. Charpinet
我们提出了一个新的脉动氦-大气（DB）白色矮星，EPIC 228782059，发现从55.1天的K2测光分析。高质量的光变曲线显示了11个独立的偶极和四极模，由此我们得到了该星星的旋转周期为34.1 ± 0.4 hr。用白色矮星演化程序构造了一系列网格，得到了一个最佳模型，其结果是M * = 0.685 ± 0.003M ε，Teff = 21，910 ± 23 K，logg=8.14±0.01 dex。这些值与Koester和Kepler从光谱学中得出的值（20，860 ± 160 K和7.94 ± 0.03 dex）相当。如果这些数值得到其他独立工作的证实或更好的约束，这将使EPIC 228782059成为已知最冷的脉动DB白色矮星之一，并将有助于测试对流的不同物理处理，以及进一步研究DB白色矮星的理论不稳定带。
We present analysis of a new pulsating helium-atmosphere (DB) white dwarf, EPIC 228782059, discovered from 55.1 days of K2 photometry. The long-duration, high-quality light curves reveal 11 independent dipole and quadruple modes, from which we derive a rotational period of 34.1 ± 0.4 hr for the star. An optimal model is obtained from a series of grids constructed using the White Dwarf Evolution Code, which returns M * = 0.685 ± 0.003M ⊙, T eff = 21,910 ± 23 K, and logg=8.14±0.01 dex. These values are comparable to those derived from spectroscopy by Koester & Kepler (20,860 ± 160 K, and 7.94 ± 0.03 dex). If these values are confirmed or better constrained by other independent works, it would make EPIC 228782059 one of the coolest pulsating DB white dwarf stars known, and would be helpful for testing different physical treatments of convection, and to further investigate the theoretical instability strip of DB white dwarf stars.