An 18.9-minute Blue Large-Amplitude Pulsator Crossing the "Hertzsprung Gap" of Hot Subdwarfs

作     者：Lin, Jie Wu, Chengyuan Wang, Xiaofeng Németh, Péter Xiong, Heran Wu, Tao Filippenko, Alexei V. Cai, Yongzhi Brink, Thomas G. Yan, Shengyu Zeng, Xiangyun Luo, Yangping Xiang, Danfeng Zhang, Jujia Zheng, WeiKang Yang, Yi Mo, Jun Xi, Gaobo Zhang, Jicheng Iskandar, Abdusamatjan Esamdin, Ali Jiang, Xiaojun Sai, Hanna Wei, Zixuan Chen, Liyang Guo, Fangzhou Chen, Zhihao Li, Wenxiong Lin, Weili Lin, Han Zhang, Xinghan 

作者机构：Physics Department Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Beijing Planetarium Beijing Academy of Sciences and Technology Beijing100044 China Astronomical Institute of the Czech Academy of Sciences Fričova 298 Ondřejov25165 Czech Republic *** Fo tér 1 Malomsok8533 Hungary Research School of Astronomy & Astrophysics Australian National University Canberra2611 Australia Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Institute of Theoretical Physics Shanxi University Taiyuan030006 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Center for Astronomy and Space Sciences China Three Gorges University Yichang443000 China Department of Astronomy China West Normal University Nanchong637002 China Department of Astronomy Beijing Normal University Beijing100875 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi830011 China National Astronomical Observatories of China Chinese Academy of Sciences Beijing100012 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2022年

核心收录：

主　　题：Helium 

摘      要：Blue large-amplitude pulsators (BLAPs) represent a new and rare class of hot pulsating stars with unusually large amplitudes and short periods. Up to now, only 24 confirmed BLAPs have been identified from more than one billion monitored stars, including a group with pulsation period longer than ∼ 20 min (classical BLAPs, hereafter) and the other group with pulsation period below ∼ 8 min (high-gravity BLAPs ). The evolutionary path that could give rise to such kinds of stellar configurations is unclear. Here we report on a comprehensive study of the peculiar BLAP discovered by the Tsinghua University - Ma Huateng Telescopes for Survey (TMTS), TMTS J035143.63+584504.2 (TMTS-BLAP-1). This new BLAP has an 18.9 min pulsation period and is similar to the BLAPs with a low surface gravity and an extended helium-enriched envelope, suggesting that it is a classical BLAP1 at the shortest-period end. In particular, the long-term monitoring data reveal that this pulsating star has an unusually large rate of period change, P/P = 2.2×10-6yr-1. Such a significant and positive value challenges its origins from both helium-core pre-white-dwarfs and core helium-burning subdwarfs, but is consistent with that derived from shell helium-burning subdwarfs. The particular pulsation period and unusual rate of period change indicate that TMTS-BLAP-1 is at a short-lived (∼ 106yr) phase of shell-helium ignition before the stable shell-helium burning;in other words, TMTS-BLAP-1 is going through a Hertzsprung gap of hot subdwarfs. The discovery of TMTS-BLAP1 possibly opens a new window to explore those rare pulsators that evolved from stripped-envelope stars. Copyright © 2022, The Authors. All rights reserved.