@article{94e23bbb181f4301b7b22df9b7de1abe,
title = "Possible detection of coronal mass ejections on late-type main-sequence stars in LAMOST medium-resolution spectra",
abstract = "Context. Stellar coronal mass ejections (CMEs) are the primary driver of exoplanetary space weather and may affect the habitability of exoplanets. However, detections of possible stellar CME signatures are extremely rare. Aims. This work aims to detect stellar CMEs from time-domain spectra observed through the LAMOST Medium-Resolution Spec-troscopic Survey (LAMOST-MRS). Our sample includes 1 379 408 LAMOST-MRS spectra of 226 194 late-type main-sequence stars (Teff < 6000 K, log[g/(cm sx2)] > 4.0). Methods. We first identified stellar CME candidates by examining the asymmetries of Hα line profiles and then performed double Gaussian fitting for Hα contrast profiles (differences between the CME spectra and reference spectra) of the CME candidates to analyse the temporal variation in the asymmetric components. Results. Three stellar CME candidates were detected on three M dwarfs. The Hα and Mg I triplet lines (at 5168.94 {\~A}, 5174.13 {\~A}, and 5185.10 {\~A}) of candidate 1 all exhibit a blue-wing enhancement, and the corresponding Doppler shift of this enhancement shows a gradually increasing trend. The Hα line also shows an obvious blue-wing enhancement in candidate 2. In candidate 3, the Hα line shows an obvious red-wing enhancement, and the corresponding projected maximum velocity exceeds the surface escape velocity of the host star. The lower limit of the CME mass is estimated to be sim;8 - 1017 g to 4 - 1018 g for these three candidates.",
keywords = "Stars: activity, Stars: late-type, Stars: solar type, Sun: coronal mass ejections (CMEs), Techniques: spectroscopic",
author = "Lu, \{Hong Peng\} and Hui Tian and Zhang, \{Li Yun\} and Christoffer Karoff and Chen, \{He Chao\} and Shi, \{Jian Rong\} and Hou, \{Zhen Yong\} and Chen, \{Ya Jie\} and Yu Xu and Wu, \{Yu Chuan\} and Cao, \{Dong Tao\} and Wang, \{Jiang Tao\}",
note = "Funding Information: Acknlwo edgemen. This work is supported by the NSFC grants 12103004, 11825301 and 11790304, the fellowship of China National Postdoctoral Program for Innovative Talents (BX2021017), and the Strategic Priority Research Program of CAS (XDA17040507). We thank the referee and Professor Shenghong Gu for the very constructive suggestions and helpful comments. Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences. Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. Part of the data in this paper was collected by the TESS mission and downloaded from the Mikulski Archive for Space Telescopes (MAST). This research has made use of the SIM-BAD database, operated at CDS, Strasbourg, France. This work uses the software TOPCAT (Taylor 2005). Publisher Copyright: {\textcopyright} 2022 H. Lu et al.",
year = "2022",
month = jul,
doi = "10.1051/0004-6361/202142909",
language = "English",
volume = "663",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
}