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The X-ray Supersoft Source State of Optical Novae
Optical novae (i.e. thermonuclear outbursts of White Dwarfs in binary systems) are among the brightest objects in galaxies. Optical novae have been identified as a main contributor to supersoft X-ray sources (SSS) in nearby galaxies in an analysis of XMM-Newton, Chandra and ROSAT archival data of M31 and M33 (Pietsch et al. 2005, 2006). 21 optical novae have been detected. Optical novae show up as supersoft X-ray sources when the ejected envelope of the White Dwarf gets transparent to the X-ray emission emitted from its Hydrogen burning surface. From the delay of the onset of the X-ray emission and the duration and X-ray spectrum, one can determine the ejected and burned mass during the outburst as well as other binary parameters. The big advantage of observations of the center area of M31 is that many novae can be monitored in the field of view of the instruments at the same time (Fig. 1).
Fig 1: The optical image (left, obtained at the Calar-Alto observatory near Granada in Spain) shows the outburst of a nova in the Andromeda galaxy M31 in optical light (light curve in green). About 180 days after the optical outburst the nova was detected as supersoft X-ray source. This is demonstrated in the Chandra image (right) and the blue X-ray light curve measured with XMM-Newton and Chandra.
Links to special pages of the project:Catalogs of Optical Nova in Nearby Galaxies
Supersoft Sources in M31
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Last update: 2010-02-01 by H. Steinle
Contact person: W. Pietsch and F. Haberl
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