XRISM/Xtend Transient Search (XTS) detected an X-ray flare from a T Tauri star CVSO 220
ATel #17413; A. Miyamoto (UOsaka), Y. Terashima (Ehime 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), 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. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), M. Yoshimoto (Ehime U.)
on 23 Sep 2025; 13:32 UT
Credential Certification: Yuichi Terashima (terashima.yuichi.mc@ehime-u.ac.jp)
Subjects: X-ray, Transient, Variables, Young Stellar Object
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J0525+0201 on 2025-09-22 TT. The source position is determined to be (R.A., Dec.) = (81.416, 2.022) with a systematic error of ∼ 40 arcsec. One of the plausible counterparts is a T Tauri star CVSO 220 at 350 pc, also catalogued as Gaia DR3 3222308873206935040, which is located ∼ 20 arcsec apart from the position of XRISM J0525+0201. All statistical uncertainties in this report are provided at a 90% confidence level unless stated otherwise.
The flare started at 2025-09-22 at around 04:46 TT and reached its peak on 2025-09-22 at around 05:20 TT. The flare exponentially decayed in 3 × 103 sec.
The peak flux is calculated as 4 × 10-11 erg s-1 cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to the statistical error. The corresponding luminosity is 5 × D350pc2 × 1032 erg s-1 by assuming the distance to XRISM J0525+0201 of D350pc.
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.
