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Rapid heartbeat in Andromeda indicates a new kind of object 
There are many kinds of celestial objects in the Universe but we are far from knowing them all. XMM-Newton may have discovered a new one: a very luminous soft X-ray source that is pulsating extremely rapidly in the central region of the Andromeda galaxy. This unusual object could be a new kind of accreting white dwarf. The spiral Andromeda galaxy (M31), only 2.5 million light years away, is in many respects similar to our own. Because it is inclined to our line-of-sight there is less intervening material in the way and thus the many hundreds of X-ray sources that it contains can easily be observed. Previous X-ray missions, such as Einstein and ROSAT, and NASA's Chandra observatory, which is currently operating, had together detected several hundred sources throughout the Andromeda galaxy. In two recent observations, XMM-Newton's EPIC-pn and EPIC-MOS cameras detected most of the previously known sources in Andromeda's central region, but also found 10 objects that have significantly brightened or dimmed between June and December 2000.
To find out more about these objects, and to read the rest of this article, go to the ESA Science site.
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