Spectroscopy of the brightest optical counterparts of X-ray sources in the direction of M~31 and M~33

Abstract

Recent surveys of the Local Group spiral Galaxies M31 and M33 with XMM-Newton yielded a large number of X-ray sources. As part of the effort to identify and classify the objects responsible for this X-ray emission, we have obtained optical spectra of the brightest optical counterparts of the identified X-ray sources, using the 1.3m Skinakas Telescope. Most of these objects are foreground star candidates. The purpose of the present study is to confirm this identification and to explore the compatibility between the optical spectral classification and the observed X-ray properties of the sources. We have obtained optical spectra for the 14 brightest optical counterparts of X-ray sources identified by XMM-Newton in the direction of M31 and for 21 optical counterparts in the direction of M33, using the 1.3m Skinakas telescope in Crete, Greece. All of the M31 sources and all but one of the M33 sources were confirmed to be foreground stars, of spectral types between A and M. One of the stars is a late M dwarf with H-alpha emission, a flare star, also displaying strong X-ray variability. One of the M~33 sources (lying within the D25 ellipse) corresponds to a previously known background galaxy, LEDA 5899.

arXiv comment9 pages, 12 figures, accepted in A&A

References in corpus (10)

• The USNO-B Catalog
• Flares from small to large: X-ray spectroscopy of Proxima Centauri with XMM-Newton
• The Distance to the M31 Globular Cluster System
• Optical novae: the major class of supersoft X-ray sources in M 31
• XMM-Newton survey of the Local Group galaxy M 33
• XMM-Newton survey of M 31
• A Synoptic X-ray Study of M31 with the Chandra-HRC
• The X-ray binary population in M33: I. Source list and luminosity function
• Some Like it Hot: The X-Ray Emission of The Giant Star YY Mensae
• Deep XMM-Newton survey of M33

Cited by in corpus (8)

• The deep XMM-Newton Survey of M 31
• Chandra ACIS Survey of M33 (ChASeM33): A First Look
• Comparing Chandra and Hubble in the Northern Disk of M31
• A Deep XMM-Newton Survey of M33: Point Source Catalog, Source Detection and Characterization of Overlapping Fields
• The Chandra ACIS Survey of M33 (ChASeM33): Transient X-ray Sources Discovered in M33
• Spectroscopy of the bright optical counterparts of X-ray sources in the direction of M 31. II
• Monitoring the X-ray Variability of Bright X-ray Sources in M33
• Photometry and spectroscopy of the newly discovered eclipsing binary GSC 4589-2999