XRISM/Xtend Transient Search (XTS) detected an X-ray flare from High Proper Motion Star UCAC4 661-042690
ATel #17049; H. Sugai (Chuo U.), K. Fukushima, K. Hayashi, Y. Kanemaru, S. Ogawa, T. Yoshida (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), T. Kohmura (TUS), Y. Maeda (JAXA), M. Mizumoto (UTEF), N. Nagashima (Chuo U.), M. Nobukawa (NUE), K. Pottschmidt (UMBC, NASA GSFC, CRESST), M. Shidatsu (Ehime U.), Y. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yanagi (Chuo U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Osaka U.)
on 24 Feb 2025; 10:40 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 J0604+4209 on 2025-02-23 TT. The source position is determined to be (R.A., Dec.) = (90.974, 42.144), with a systematic error of ∼ 40 arcsec. A plausible counterpart is M2 dwarf high proper motion star UCAC4 661-042690 which corresponds to the X-ray source 4XMM J060352.2+420833. UCAC4 661-042690 is located ∼ 17 arcsec apart from the position of XRISM J0604+4209.
The flare started at 2025-02-23 at ∼ 01:00 with the flux of 7 × 10-14 erg s-1 cm-2 and reached its peak on 2025-02-23 at ∼ 01:35 with the flux of 4 × 10-13 erg s-1 cm-2. The flare exponentially decayed in 3 × 103 sec.
The above fluxes are in the 0.4 – 2.0 keV. The corresponding peak luminosity is 4 × 1029 erg s-1 cm-2 when we assume the distance to XRISM J0604+4209 of D96 pc.
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.
