Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-11-08
Astronomy and Astrophysics
Astrophysics
8 pages, 6 figures, 2 tables, PASJ in press
Scientific paper
We report a serendipitous detection of an intense X-ray flare from the Tycho reference source HD 161084 during a Suzaku observation of the Galactic Center region for 20 ks. The X-ray Imaging Spectrometer (XIS) recorded a flare from this A1-type dwarf or subgiant star with a flux of 1.4x10^{-12} erg s^{-1} cm^{-2} (0.5--10 keV) and a decay time scale of 0.5 hr. The spectrum is hard with a prominent Fe XXV K alpha emission line at 6.7 keV, which is explained by a 5 keV thin-thermal plasma model attenuated by a 1.4x10^{21} cm^{-2} extinction. The low extinction, which is consistent with the optical reddening, indicates that the source is a foreground star toward the Galactic Center region. Based on the spectroscopic parallax distance of 530 pc, the peak X-ray luminosity amounts to 1x10^{32} erg s^{-1} (0.5--10 keV). This is much larger than the X-ray luminosity of ordinary late-type main-sequence stars, and the X-ray emission is unattributable to a hidden late-type companion that comprises a wide binary system with the A-star. We discuss possible natures of HD 161084 and suggest that it is most likely an interacting binary with elevated magnetic activity in the companion such as the Algol-type system. The flux detected by Suzaku during the burst is 100 times larger than the quiescent level measured using the archived XMM-Newton and Chandra data. The large flux amplification makes this star a unique example among sources of this class.
Koyama Katsuji
Maeda Yoshitomo
Miura Junichiro
Sugawara Yasuharu
Tsuboi Yohko
No associations
LandOfFree
Suzaku Detection of an Intense X-Ray Flare from an A-type Star HD161084 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Suzaku Detection of an Intense X-Ray Flare from an A-type Star HD161084, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Suzaku Detection of an Intense X-Ray Flare from an A-type Star HD161084 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-377382