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Issue A&A Volume 369, Number 1, April I 2001 Page(s) 210 - 214 Section Formation, structure and evolution of stars DOI 10.1051/0004-6361:20010110

A&A 369, 210-214 (2001)
DOI: 10.1051/0004-6361:20010110

IR spectra of the microquasar GRS 1915+105 during a low state

E. T. Harlaftis¹, V. S. Dhillon² and A. Castro-Tirado<sup>3, 4

1</sup>  Institute of Astronomy and Astrophysics, National Observatory of Athens, PO Box 20048, Athens 118 10, Greece
²  Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
³  Instituto de Astrofísica de Andalucía (IAA-CSIC), PO Box 03004, 18080 Granada, Spain
⁴  Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA), PO Box 50727, 28080 Madrid, Spain

(Received 29 December 2000 / Accepted 12 January 2001 )

Abstract
There is controversy regarding the nature of the suspected donor star to the microquasar GRS 1915+105, and hence whether GRS 1915+105 is a high mass X-ray binary (HMXB) or a low-mass X-ray binary (LMXB). In order to clarify this issue, we obtained an infrared (J, H and K) spectrum of GRS 1915+105 in its low state which shows a steeper continuum than the prototype X-ray binary Sco X-1. We did not detect any HeII emission at 2.189 m from GRS 1915+105 in our quiescent spectrum, indicating that the line is transient and is only observed during episodes of high X-ray activity. For our instrument configuration, there is no detection of the ¹²CO lines which are characteristic of late-type stars either in GRS 1915+105 or Sco X-1.

Key words: infrared: stars -- X-ray: stars -- black hole physics -- stars: binaries -- stars: individual: GRS 1915+105

Offprint request: E. T. Harlaftis, ehh@astro.noa.gr

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