Supernova leaves behind mysterious object

This image, obtained thanks to ESA's XMM-Newton X-ray telescope on 23 August 2005, shows the aftermath of a 2000-year-old star explosion. In the heart of the central blue dot in this image, smaller than a pinpoint, likely lies a neutron star only about 20 kilometers across. The nature of this object is like nothing detected before. Scientists from the Istituto Nazionale di Astrofisica (INAF) in Milan have detected unusual X-ray pulsations. Understanding the central source's true nature will lead to new insights about supernovae, neutron stars and their evolution. Credit: ESA/XMM-Newton/A.De Luca (INAF-IASF )