Variable stars towards the bulge of M 31: The AGAPE catalogue ^*,**

¹ Laboratoire de l'Accélérateur Linéaire, Université Paris-Sud, 91405 Orsay Cedex, France
² Observatoire Midi-Pyrénées, unité associée au CNRS (UMR 5572), 57 Avenue d'Azereix, BP 826, 65008 Tarbes Cedex, France
³ CERN, 1211 Genève 23, Switzerland
⁴ Physique Corpusculaire et Cosmologie, Collège de France, laboratoire associé au CNRS-IN2P3 (UMR 7550), 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
⁵ DAPNIA/SPP, CEN Saclay, 91191 Gif-sur-Yvette, France
⁶ Department of Physics, University of Utah, 115 S 1400 E Rm 201, Salt Lake City, UT 84112-0830, USA
⁷ Observatoire Midi-Pyrénées, unité associée au CNRS (UMR 5572), 14 avenue Belin, 31400 Toulouse, France
⁸ Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
⁹ LERMA, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France

Corresponding author: M. Aurière, michel.auriere@obs-mip.fr

Received: 11 November 2003
Accepted: 23 March 2004

Abstract

We present the AGAPE astrometric and photometric catalogue of 1579 variable stars in a    field centred on M 31. This work is the first survey devoted to variable stars in the bulge of M 31. The R magnitudes of the objects and the  colours suggest that our sample is dominated by red long-period variable stars (LPV), with a possible overlap with Cepheid-like type II stars. Fits of the light curves with sinusoids suggest that a large fraction of the stars correspond to periodic or semi-periodic objects with periods longer than 100 days. Twelve nova candidates are identified. Correlations with other catalogues suggest that 2 novae could be recurrent novae and provide possible optical counterparts for 2 supersoft X-ray sources candidates observed with Chandra.