A Large X-Ray Flare from a Single Weak-Lined T Tauri Star TWA-7 Detected with MAXI GSC

作者：Uzawa Akiko^*; Tsuboi Yohko; Morii Mikio; Yamazaki Kyohei; Kawai Nobuyuki; Matsuoka Masaru; Nakahira Satoshi; Serino Motoko; Matsumura Takanori; Mihara Tatehiro; Tomida Hiroshi; Ueda Yoshihiro; Sugizaki Mutsumi; Ueno Shiro; Daikyuji Arata; Ebisawa Ken; Eguchi Satoshi; Hiroi Kazuo; Ishikawa Masaki; Isobe Naoki; Kawasaki Kazuyoshi; Kimura Masashi; Kitayama Hiroki; Kohama Mitsuhiro; Kotani Taro; Nakagawa Yujin E; Nakajima Motoki; Negoro Hitoshi; Ozawa Hiroshi

来源：Publications of the Astronomical Society of Japan, 2011, 63: S713-S716.

• stars: flare
• stars: individual (1RXS J104230.3-334014, TWA-7)
• stars: late-type
• stars: pre-main-sequence
• X-rays: stars

We present a large X-ray flare from a nearby weak-lined T Tauri star TWA-7 detected with the Gas Slit Camera (GSC) on the Monitor of All-sky X-ray Image (MAXI). The GSC captured X-ray flaring from TWA-7 with a flux of 3 x 10(-9) erg cm(-2)s(-1) in 2-20 keV band during the scan transit starting at 2010-09-07 18:24:30 (UT). The estimated X-ray luminosity at the scan in the energy band is 3 x 10(32) erg s(-1), indicating that the event is among the largest X-ray flares from T Tauri stars. Since MAXI GSC monitors a target only during a scan transit of about a minute per 92 min orbital cycle, the luminosity at the flare peak might have been higher than that detected. At the scan transit, we observed a high X-ray-to-bolometric luminosity ratio, log L(X)/L(bol) = -0.1(-0.3)(+0.2); i.e., the X-ray luminosity is comparable to the bolometric luminosity. Since TWA-7 has neither an accreting disk nor a binary companion, the observed event implies that none of those are essential to generate such big flares in T Tauri stars.

• 出版日期2011
• 单位中国科学院国家天文台