Recent discoveries of supersoft X-ray sources in M 31

Type Journal Article
Names M. Henze, W. Pietsch, F. Haberl, G. Sala, M. Hernanz, D. Hatzidimitriou, A. Rau, D. H. Hartmann, J. Greiner, M. Orio, H. Stiele, M. J. Freyberg
Publication Astronomische Nachrichten
Volume 331
Issue 2
Pages 193
Date 2010
Library Catalog NASA ADS
Abstract Classical novae (CNe) have recently been reported to represent the major class of supersoft X-ray sources (SSSs) in the central area of our neighbouring galaxy M 31. This paper presents a review of results from recent X-ray observations of M 31 with XMM-Newton and Chandra. We carried out a dedicated optical and X-ray monitoring program of CNe and SSSs in the central area of M 31. We discovered the first SSSs in M 31 globular clusters (GCs) and their connection to the very first discovered CN in a M 31 GC. This result may have an impact on the CN rate in GCs. Furthermore, in our optical and X-ray monitoring data we discovered the CN M31N 2007-11a, which shows a very short SSS phase of 29-52 days. Short SSS states (durations ≤ 100 days) of CNe indicate massive white dwarfs (WDs) that are candidate progenitors of supernovae type Ia. In the case of M31N 2007-11a, the optical and X-ray light curves suggest a binary containing a WD with M_WD > 1.0 M\sun. Finally, we present the discovery of the SSS counterpart of the CN M31N 2006-04a k. The X-ray light curve of M31N 2006-04a shows short-time variability, which might indicate an orbital period of about 2 hours. Partly based on observations with \xmmk, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and NASA.
Tags Cataclysmic Variables, M31N 2006-04a k), M31N 2007-11a, NOVAE, X-Rays: Binaries, galaxies: individual: (M 31), stars: individual: (M31N 2007-06b k
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