EDP Sciences
Free access
Volume 507, Number 2, November IV 2009
Page(s) 705 - 711
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361/200912508
Published online 08 September 2009
A&A 507, 705-711 (2009)
DOI: 10.1051/0004-6361/200912508

Spectroscopy of the bright optical counterparts of X-ray sources in the direction of M 31

P. Bonfini1, D. Hatzidimitriou1, 2, W. Pietsch3, and P. Reig2, 1

1  University of Crete, Department of Physics, PO Box 2208, 71003, Heraklion, Greece
    e-mail: paolo@physics.uoc.gr
2  IESL, Foundation for Research and Technology, 71110, Heraklion, Greece
3  Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany

Received 15 May 2009 / Accepted 17 July 2009

Context. A recent survey of the Local Group spiral galaxy M 31 with XMM-Newton yielded a large number of X-ray sources.
Aims. This is the second in a series of papers with the aim of identifying the optical counterparts of these X-ray sources.
Methods. We have obtained optical spectra for 21 bright optical counterparts of 20 X-ray sources in the direction of M 31, using the 1.3-m Skinakas telescope in Crete, Greece.
Results. For 17 of the 20 X-ray sources, we have identified the optical counterpart as a normal late type star (of type F or later) in the foreground (i.e. in the Milky Way). For two more sources, there were two possible optical counterparts, in each case, while two more objects have X-ray properties that are not compatible with the spectral characteristics of late type non-flaring stars.

Key words: galaxies: individual: M 31 -- X-rays: galaxies -- X-rays: stars

© ESO 2009