Puzzling pulsation from the heart of RCW103

In August 2005, ESA's XMM-Newton observed the centre (blue dot in the image) of the supernova remnant RCW103 - the aftermath of a 2000-year-old star explosion.

The light curve on the right of the image unambiguously shows X-ray pulsation with a period of 6.67 hours - an astonishingly long period for the young neutron star expected to lie there.

The puzzling nature of this object (1E161348-5055), reminiscent of a multimillion-year-old source, is like nothing detected before.