A huge-amplitude white-light superflare on a L0 brown dwarf discovered by GWAC survey

Author:

Xin Li-Ping1ORCID,Li Hua-li1,Wang Jing12,Han Xu-Hui1,Cai Hong-Bo1,Huang Xin-Bo2,Cao Jia-Xin2,Zhu Yi-Nan3,Wang Xiang-Gao2,Li Guang-Wei1,Ren Bin124,Gao Cheng124,Song Da124,Huang Lei1,Lu Xiao-Meng1,Bai Jian-Ying1,Qiu Yu-Lei1,Liang En-Wei2ORCID,Dai Zi-Gao56,Wang Xiang-Yu67ORCID,Wu Chao1,Deng Jing-Song14,Yang Yuan-Gui8,Wei Jian-Yan14

Affiliation:

1. CAS Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100101 , China

2. Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004 , China

3. Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100012 , China

4. School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing , China

5. Department of Astronomy, University of Science and Technology of China , Hefei 230026 , China

6. School of Astronomy and Space Science, Nanjing University , Nanjing 210093 , China

7. Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education , Nanjing 210093 , China

8. School of Physics and Electronic Information, Huaibei Normal University , Huaibei 235000 , China

Abstract

ABSTRACT White-light superflares from ultra-cool stars are thought to be resulted from magnetic reconnection, but the magnetic dynamics in a fully convective star is not clear yet. In this paper, we report a stellar superflare detected with the ground wide angle camera (GWAC), along with rapid follow-ups with the F60A, Xinglong 2.16-m, and LCOGT telescopes. The effective temperature of the counterpart is estimated to be 2200 ± 50 K by the BT-Settl model, corresponding to a spectral type of L0. The R-band light curve can be modelled as a sum of three exponential decay components, where the impulsive component contributes a fraction of 23 per cent of the total energy, while the gradual and the shallower decay phases emit 42 per cent and 35 per cent of the total energy, respectively. The strong and variable Balmer narrow emission lines indicate the large amplitude flare is resulted from magnetic activity. The bolometric energy released is about 6.4 × 1033 erg, equivalent to an energy release in a duration of 143.7 h at its quiescent level. The amplitude of Δ R = −8.6 mag (or Δ V = −11.2 mag), placing it one of the highest amplitudes of any ultra-cool star recorded with excellent temporal resolution. We argue that a stellar flare with such rapidly decaying and huge amplitude at distances greater than 1 kpc may be false positive in searching for counterparts of catastrophic events such as gravitational wave events or gamma-ray bursts, which are valuable in time-domain astronomy and should be given more attention.

Funder

National Natural Science Foundation of China

Chinese Academy of Sciences

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. The White-light Superflares from Cool Stars in GWAC Triggers;The Astrophysical Journal;2024-08-01

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