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LEIA discovery of the longest-lasting and most energetic stellar X-ray flare ever detected

Authors :
Mao, Xuan
Liu, He-Yang
Wang, Song
Ling, Zhixing
Yuan, Weimin
Cheng, Huaqing
Pan, Haiwu
Li, Dongyue
Favata, Fabio
Ji, Tuo
Zhang, Jujia
Zhao, Xinlin
Wan, Jing
Cai, Zhiming
Castro-Tirado, Alberto J.
Dai, Yanfeng
Deng, Licai
Ding, Xu
Ji, Kaifan
Jin, Chichuan
Lei, Yajuan
Li, Huali
Lin, Jun
Liu, Huaqiu
Liu, Mingjun
Liu, Shuai
Liu, Yuan
Sun, Hui
Sun, Shengli
Sun, Xiaojin
Shi, Jianrong
Wang, Jianguo
Wang, Jingxiu
Wang, Wenxin
Wei, Jianyan
Xin, Liping
Xiong, Dingrong
Zhang, Chen
Zhang, Wenda
Zhang, Yonghe
Zhang, Xiaofeng
Zhao, Donghua
Zhou, Guiping
Publication Year :
2024

Abstract

LEIA (Lobster Eye Imager for Astronomy) detected a new X-ray transient on November 7, 2022, identified as a superflare event occurring on a nearby RS CVn-type binary HD 251108. The flux increase was also detected in follow-up observations at X-ray, UV and optical wavelengths. The flare lasted for about 40 days in soft X-ray observations, reaching a peak luminosity of ~1.1 * 10^34 erg/s in 0.5-4.0 keV, which is roughly 60 times the quiescent luminosity. Optical brightening was observed for only one night. The X-ray light curve is well described by a double "FRED" (fast rise and exponential decay) model, attributed to the cooling process of a loop arcade structure formed subsequent to the initial large loop with a half-length of ~1.9 times the radius of the host star. Time-resolved X-ray spectra were fitted with a two-temperature apec model, showing significant evolution of plasma temperature, emission measure, and metal abundance over time. The estimated energy released in the LEIA band is ~3 * 10^39 erg, suggesting this is likely the most energetic X-ray stellar flare with the longest duration detected to date.<br />Comment: submitted to ApJL, 22 pages, 9 figures, 7 tables

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2410.17999
Document Type :
Working Paper