_version_ 1866908756612218880
author Zhao, Guoying
Zheng, WeiKang
Shen, Rong-Feng
Shui, Qingcang
Li, Dongyue
Zhou, Chang
Zheng, Tianci
Yuan, Weimin
Liu, HeYang
Ge, Chong
Wang, Junfeng
Filippenko, Alexei V.
Brink, Thomas G.
Forman, Jordan
Gutierrez, Mayra
Jones, Isabelle
Kaur, Ravjit
Leonhardes-Barboza, Naunet
Mengistu, Petra
Patel, Avi
Skemer, Andrew
Uppal, Anavi
Wolff, Nicole
Woodland, Michele N.
author_facet Zhao, Guoying
Zheng, WeiKang
Shen, Rong-Feng
Shui, Qingcang
Li, Dongyue
Zhou, Chang
Zheng, Tianci
Yuan, Weimin
Liu, HeYang
Ge, Chong
Wang, Junfeng
Filippenko, Alexei V.
Brink, Thomas G.
Forman, Jordan
Gutierrez, Mayra
Jones, Isabelle
Kaur, Ravjit
Leonhardes-Barboza, Naunet
Mengistu, Petra
Patel, Avi
Skemer, Andrew
Uppal, Anavi
Wolff, Nicole
Woodland, Michele N.
contents Stellar flares are an intense stellar activity that can significantly impact the atmospheric composition of the surrounding planets and even the possible existence of life. During such events, the radiative energy of the star is primarily concentrated in the optical and X-ray bands, with the X-ray flux potentially increasing by tens or even hundreds of times. Einstein Probe (EP) detected a new X-ray transient EP J2322.1-0301 on 27 September 2024. Its spatial localization shows a high positional coincidence with the nearby high proper motion K-type star PM J23221-0301. Follow-up X-ray observations confirmed the flux enhancement of the source, while optical spectroscopic monitoring revealed time-variable features, particularly the disappearance of the H-alpha emission line. This X-ray flare is consistent with a characteristic fast-rise-exponential-decay (FRED) light curve, with a rise timescale of 1.4 ks, a decay timescale of 5.7 ks, and a total duration of about 7.1 ks. The peak luminosity in the 0.5-4.0 keV energy band reached about 1.3 x 10^31 erg s^-1, with a total energy release of about 9.1 x 10^34 erg, consistent with the empirical energy correlations observed in magnetic-reconnection-driven stellar flares, as inferred from the multitemperature plasma structure and H-alpha-X-ray energy correlation. This discovery underscores EP's capability in understanding stellar magnetic activity via observing stellar transients.
format Preprint
id arxiv_https___arxiv_org_abs_2512_16679
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Einstein Probe Discovery of an X-ray Flare from K-type Star PM J23221-0301
Zhao, Guoying
Zheng, WeiKang
Shen, Rong-Feng
Shui, Qingcang
Li, Dongyue
Zhou, Chang
Zheng, Tianci
Yuan, Weimin
Liu, HeYang
Ge, Chong
Wang, Junfeng
Filippenko, Alexei V.
Brink, Thomas G.
Forman, Jordan
Gutierrez, Mayra
Jones, Isabelle
Kaur, Ravjit
Leonhardes-Barboza, Naunet
Mengistu, Petra
Patel, Avi
Skemer, Andrew
Uppal, Anavi
Wolff, Nicole
Woodland, Michele N.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Stellar flares are an intense stellar activity that can significantly impact the atmospheric composition of the surrounding planets and even the possible existence of life. During such events, the radiative energy of the star is primarily concentrated in the optical and X-ray bands, with the X-ray flux potentially increasing by tens or even hundreds of times. Einstein Probe (EP) detected a new X-ray transient EP J2322.1-0301 on 27 September 2024. Its spatial localization shows a high positional coincidence with the nearby high proper motion K-type star PM J23221-0301. Follow-up X-ray observations confirmed the flux enhancement of the source, while optical spectroscopic monitoring revealed time-variable features, particularly the disappearance of the H-alpha emission line. This X-ray flare is consistent with a characteristic fast-rise-exponential-decay (FRED) light curve, with a rise timescale of 1.4 ks, a decay timescale of 5.7 ks, and a total duration of about 7.1 ks. The peak luminosity in the 0.5-4.0 keV energy band reached about 1.3 x 10^31 erg s^-1, with a total energy release of about 9.1 x 10^34 erg, consistent with the empirical energy correlations observed in magnetic-reconnection-driven stellar flares, as inferred from the multitemperature plasma structure and H-alpha-X-ray energy correlation. This discovery underscores EP's capability in understanding stellar magnetic activity via observing stellar transients.
title Einstein Probe Discovery of an X-ray Flare from K-type Star PM J23221-0301
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2512.16679