Variable white dwarfs in TMTS: Asteroseismological analysis of a ZZ Ceti star, TMTS J17184064+2524314

• Published in: arXiv.org
• Main Authors: Guo, Jincheng, Chen, Yanhui, Yang, Yonghui, Wang, Xiaofeng, Lin, Jie, Xiao-Yu, Ma, Gaobo Xi, Mo, Jun, Filippenko, Alexei V, Brink, Thomas G, Zong, Weikai, Huahui Yan, Zhao, Jingkun, Zeng, Xiangyun, Chen, Zhihao, Esamdin, Ali, Guo, Fangzhou, Abdusamatjan Iskandar, Jiang, Xiaojun, Li, Wenxiong, Liu, Cheng, Shi, Jianrong, Song, Xuan, Wang, Letian, Xiang, Danfeng, Shengyu Yan, Zhang, Jicheng
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 26.01.2024
• Subjects: Light curve; Luminosity; Northern sky; Rotational spectra; Sky surveys (astronomy); Stellar seismology; Variable stars; White dwarf stars
• ISSN: 2331-8422

The Tsinghua University-Ma Huateng Telescope for Survey (TMTS) has been constantly monitoring the northern sky since 2020 in search of rapidly variable stars. To find variable white dwarfs (WDs), the TMTS catalog is cross-matched with the WD catalog of Gaia EDR3, resulting in over 3000 light curves of WD candidates. The WD TMTS J17184064+2524314 (hereafter J1718) is the second ZZ~Ceti star discovered among these common sources. Based on the light curves from TMTS, follow-up photometric observations, and TESS, 10 periods and 3 combination periods are detected. A rotation period of \(25.12\pm0.18\) hr is derived, according to the identified rotational splitting. Our spectroscopic observation indicates that this WD belongs to DA type with \(T_{\rm eff}=11,670\pm604\) K, log \(g=8.16\pm0.36\), \(M = 0.70\pm0.23\) M\(_{\odot}\), and age=\(0.51\pm0.34\) Gyr. Based on core-parameterized asteroseismological model grids (\(\geqslant\) 14 million), we derive a best-fit solution of \(T_{\rm eff}=11,640\pm20\) K, log \(g=8.267\pm0.008\), and \(M = 0.750\pm0.005\) M\(_{\odot}\) for J1718, consistent with the spectral fitting results. For this WD, the corresponding carbon and oxygen abundances in the core are 0.43 and 0.57, respectively. The distance derived from the intrinsic luminosity given by asteroseismology is \(64\pm15\) pc, in accord with the distance of \(70.1\pm0.2\) pc from Gaia DR3 within the uncertainties.