On the radio emitting high mass X-ray binary LS 5039

被引:43
作者
Clark, JS [1 ]
Reig, P
Goodwin, SP
Larionov, VM
Blay, P
Coe, MJ
Fabregat, J
Negueruela, I
Papadakis, I
Steele, IA
机构
[1] Univ Sussex, CPES, Ctr Astron, Brighton BN1 9QH, E Sussex, England
[2] UCL, Dept Phys & Astron, London WC1E 6BT, England
[3] Univ Crete, Dept Phys, Iraklion 71003, Greece
[4] Fdn Res & Technol Hellas, Iraklion 71110, Greece
[5] Univ Wales Coll Cardiff, Dept Phys & Astron, Cardiff CF24 3YB, S Glam, Wales
[6] St Petersburg State Univ, Inst Astron, St Petersburg 198904, Russia
[7] Isaac Newton Inst Chile, St Petersburg Branch, Santiago, Chile
[8] Univ Valencia, Dept Astron, E-46100 Valencia, Spain
[9] Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England
[10] Liverpool John Moores Univ, Astrophys Res Inst, Liverpool L41 1LD, Merseyside, England
关键词
stars : early-type; stars : individual : LS 5039; X-rays; stars; binaries;
D O I
10.1051/0004-6361:20010919
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present new optical - near-IR spectroscopic and photometric observations of the newly discovered galactic microquasar LS 5039, which indicate a classification for the mass donor in the system of O6.5V((f)). Optical spectroscopy and photometry shows no variability over a timescale of years, and we find no evidence of modulation by, or emission from the compact companion in these data. However significant photometric variability (similar to0.4 mag) is present in the H and K bands between 1995-2000. Such variability has been observed in other radio bright X-ray binaries where it has been attributed to synchrotron emission from the jet. However, given the non-thermal spectral index of the radio emission in LS 5039 this explanation appears unlikely, predicting a near-IR flux similar to3 orders of magnitude too small to contribute significantly at such wavelengths. Nightly optical photometry over a 21 day period between 2000 May-June reveals variability at a level of a few hundredths of a magnitude, with no periodicity or long term trend visible. Likewise, while the radio lightcurves show moderate variability (similar to 20 per cent of the mean flux density) we find no evidence of periodic modulation - Monte Carlo simulations constrain any such periodic variability to <4 per cent modulation at 2.25 GHz. The differences in behaviour between LS 5039 and Cygnus X-1 - the most closely related radio emitting High Mass X-ray Binary - are likely to be a result of the weaker stellar wind and probable greater orbital separation of LS 5039 compared to Cyg X-1.
引用
收藏
页码:476 / 483
页数:8
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