Este fue
tu cielo.

Cooling Neutron Star

At the center of supernova remnant Cassiopeia A is a neutron star, the collapsed core of a massive star. The light from the supernova explosion reached Earth about 350 years ago. This composite X-ray and optical image shows the expanding debris cloud, which spans about 15 light-years. The neutron star is still hot enough to emit X-rays, and it is slowly cooling.