A huge H-alpha line flare from the RS CVn binary system UX Ari detected with SCAT at the follow-up of MAXI/GSC detection
ATel #16423; N. Nemoto, S. Urabe, N. Nagashima, Y. Tsuboi(Chuo U.), W. Iwakiri (Chiba U.), H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), S. Nawa, E. Goto (Chuo U.), M. Shidatsu (Ehime U.), I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA), Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani, Y. Okada (Kyoto U.), M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC)
on 29 Jan 2024; 16:30 UT
Credential Certification: Yohko Tsuboi (tsuboi@phys.chuo-u.ac.jp)
Subjects: Optical, X-ray, Binary, Star
After the detection of an X-ray flare with MAXI/GSC, a huge H-alpha line flare was detected from the RS-CVn type binary UX Ari with the Spectroscopic Chuo university Astronomical Telescope (SCAT), which is located in the Korakuen campus of Chuo University in Tokyo, Japan. The nova-alert system (Negoro et al. 2016) triggered the X-ray flare at 04:25:16 UT on 2024 January 27, and the flux reached the peak at the next scan transit at 05:58:02 UT on the same day with a value of 80 mCrab in the 4 – 10 keV band. If we assume that the flare flux decayed exponentially with time, the estimated e-folding time of this flare is 2 × 104 sec.
We carried out a follow-up observation with SCAT, which consists of a 355 mm diameter Kasai Trading GS-350 RC/TR telescope and an ATIK 460EX CCD camera with a Shelyak Alpy 600 spectrometer whose spectral resolution R is 600. The SCAT observation was made at 08:59 – 14:57 UT 2024 January 27 with a net exposure of 9960 sec. The observed H-alpha emission line indicated the equivalent width of 17 Å at 08:59 UT, which is among the largest level for RS CVn systems, and it decayed to 6 Å 14:57 UT. The e-folding time during the decay phase was estimated to be 2.1 × 104 sec. The previously observed equivalent widths of the H-alpha line during flares of UX Ari is ~5 Å at most (e.g. Kawai et al 2022). These results show that the H-alpha line intensity of this flare is distinguished.
