XRISM/Xtend Transient Search (XTS) detected an X-ray flare possibly from a K or G-type star
ATel #17454; M. Yoshimoto (Ehime U.), Y. Tsuboi (Chuo U.), K. Fukushima, Y. Kanemaru, S. Ogawa, Y. Uchida, T. Yoneyama (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), T. Hakamata (UOsaka), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), C. Kang (Ehime U.), T. Kiyomoto (Saitama U.), T. Kohmura (TUS), H. Kuramoto (UOsaka), J. Kurashima (U. of Miyazaki), Y. Maeda (JAXA), H. Matsumoto (UOsaka), T. Matsushima (U. of Miyazaki), A. Miyamoto (UOsaka), M. Mizumoto (UTEF), K. Mori (U. of Miyazaki), Y. Motogami (Saitama U.), N. Nagashima (Chuo U.), T. Narita (Kyoto U.), M. Nobukawa (NUE), H. Noda (Tohoku U.), Y. Sakamoto (Tohoku U.), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), H. Takahashi (Hiroshima U.), T. Takagi (Ehime U.), S. Takatuska (UOsaka), R. Takemoto (U. of Miyazaki), Y. Terada (Saitama U., JAXA), Y. Terashima (Ehime U.), H. Uchida (Kyoto U.)
on 27 Oct 2025; 07:05 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J2202-3206 on 2025-10-25 TT. The source position is determined to be (R.A., Dec.) = (330.444, -32.106), with a systematic error of ∼ 40 arcsec. A plausible counterpart is the K or G-type star Gaia DR3 6612914313328531328, which is located ∼ 9 arcsec apart from the position of XRISM J2202-3206. Plausible X-ray counterparts are 2CXO J220146.8-320629, 4XMM J220147.0-320630.
The flare reached its peak on 2025-10-25 at ∼ 02:28. The flare exponentially decayed in 8 × 103 sec.
The peak flux is calculated as 2 × 10-12 erg s-1 cm-2 (0.4 – 10.0 keV). The corresponding luminosity is 2 × 1032 erg s-1, assuming a distance to XRISM J2202-3206 of 1 kpc, based on Gaia DR3 6612914313328531328.
We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimated the systematic error for the source position from the separations between the detected sources with the corresponding counterparts in the same field of view.
