XRISM/Xtend Transient Search (XTS) reported the second detection of a prestellar flare from 2MASS J11414215-6521298
ATel #16775; S. Ogawa, K. Fukushima, K. Hayashi, Y. Kanemaru, 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), 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 15 Aug 2024; 11:56 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient, Young Stellar Object
Referred to by ATel #: 16777
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-14 TT. This is the second report by XRISM of a brightening of this source following the last one (ATel #16774). The source position is (R.A., Dec.) = (175.418, -65.363), with a systematic error of ∼ 40 arcsec. As described below, the second prestellar flare is by a factor of 7 brighter than the first one. All statistical uncertainties in this report will be provided as a 90% confidence level unless stated otherwise.
Despite rough constraints due to a bad time interval of XRISM, the start and peak times of this flare would have been 2024-08-14 02:07 – 02:23 TT and 2024-08-14 03:21 – 03:56 TT, respectively. The flare exponentially decayed with an e-folding time of 11 (+1.4/-1.2) × 103 sec, which is derived by fitting the 0.4 – 10.0 keV light curve with a constant + exponential model in the QDP software package.
In order to calculate the source flux, we fit the spectrum in the flare peak phase with an unabsorbed APEC model with a temperature of kT = 3.3 (+1.2/-0.8) keV. Then, the model flux was estimated to be 9.4 (+1.3/-1.2) × 10-12 erg s-1cm-2 (0.4 – 10.0 keV). A systematic error of roughly 20% should be added to statistical errors of the flux. Corresponding luminosity is 1.2 (+0.2/-0.2) × 10 31 erg s-1 by assuming the distance to 2MASS J11414215-6521298 of 101 pc.
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.
