X-ray spectral variability during an outburst in V1118 Ori

被引:27
作者
Audard, M
Güdel, M
Skinner, SL
Briggs, KR
Walter, FM
Stringfellow, G
Hamilton, RT
Guinan, EF
机构
[1] Columbia Astrophys Lab, New York, NY 10027 USA
[2] Paul Scherrer Inst, CH-5232 Villigen, Switzerland
[3] Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA
[4] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA
[5] Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA
关键词
accretion; accretion disks; circumstellar matter; stars : coronae; stars : individual (V1118 Orionis); stars : pre-main-sequence; X-rays : stars;
D O I
10.1086/499237
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present results from a multiwavelength campaign to monitor the 2005 outburst of the low-mass young star V1118 Ori. Although our campaign covers the X-ray, optical, infrared, and radio regimes, we focus in this Letter on the properties of the X-ray emission in V1118 Ori during the first few months after the optical outburst. Chandra and XMM-Newton detected V1118 Ori at three epochs in early 2005. The X-ray flux and luminosity stayed similar within a factor of 2 and at the same level as in a preoutburst observation in 2002. The hydrogen column density showed no evidence for variation from its modest preoutburst value of N-H similar to 3 x 10(21) cm(-2). However, a spectral change occurred from a dominant hot plasma (similar to 25 MK) in 2002 and in 2005 January to a cooler plasma (similar to 8 MK) in 2005 February and in 2005 March. We hypothesize that the hot magnetic loops high in the corona were disrupted by the closing in of the accretion disk due to the increased accretion rate during the outburst, whereas the lower cooler loops were probably less affected and became the dominant coronal component.
引用
收藏
页码:L81 / L84
页数:4
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