4U 1957+11: a persistent low-mass X-ray binary and black hole candidate in the high state?

被引：24
作者：
Wijnands, R
Miller, JM
van der Klis, M
机构：
[1] MIT, Ctr Space Res, Cambridge, MA 02139 USA
[2] Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands
来源：
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2002年 / 331卷 / 01期
关键词：
accretion; accretion discs; binaries : close; stars : individual : 4U 1957+11; X-rays : stars;
D O I：
10.1046/j.1365-8711.2002.05137.x
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
We report on several pointed Rossi X-ray Timing Explorer observations of the enigmatic low-mass X-ray binary (LMXB) 4U 1957+11 at different X-ray luminosities. The luminosity of the source varied by more than a factor of 4 on time-scales of months to years. The spectrum of the source tends to become harder when its luminosity increases. Only very weak (1-2 per cent rms amplitude, 0.001-10 Hz, 2-60 keV) rapid X-ray variability was observed during the observations. A comparison of the spectral and temporal. behaviour of 4U 1957+11 with other X-ray binary systems, in particular LMC X-3, indicates that 4U 1957+11 is likely to be a persistent LMXB harbouring a black hole and it is persistently in the black hole high state. If confirmed, it would be the only such system known.
引用
收藏
页码：60 / 70
页数：11
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