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Session 49 - Elliptical Galaxies & Bulges.
Display session, Thursday, January 08
Exhibit Hall,
EXOSAT observed M31 on three occasions: in 1983 on July 2 and July 27, and in 1984 on December 29. We have analyzed the data restored by the HEASARC in order to study the time variability of the M31 bulge population. The images (from the Low Energy, LE, telescopes and the Channel Multiplier Array, CMA, detectors) obtained in 1983, show the presence of two sources in the core of M31 not detected in the 1984 observation. The source locations are within 2.5 arcmin of the M31 nucleus. For the brighter source a variation in count rate is observed between the two 1983 observations suggesting a transient nature. The source variability is also confirmed by comparing the EXOSAT results with previous Einstein HRI and more recent ROSAT PSPC observations available in the archive.
