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

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 ab...

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Bibliographic Details
Published in:arXiv.org 2024-10
Main Authors: Mao, Xuan, He-Yang, Liu, 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, Xu, Ding, Ji, Kaifan, Jin, Chichuan, Yajuan Lei, 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, Jianyan Wei, Xin, Liping, Xiong, Dingrong, Zhang, Chen, Zhang, Wenda, Zhang, Yonghe, Zhang, Xiaofeng, Zhao, Donghua, Zhou, Guiping
Format: Article
Language:English
Subjects:
Binary stars
Brightening
Emission spectra
Light curve
Luminosity
Plasma temperature
Soft x rays
Stellar flares
Time measurement
X ray spectra
X-ray astronomy
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Summary: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.
ISSN:2331-8422