Credit: (Top) NASA/Chandra X-ray Observatory; (Bottom) redrawn with permission from Fridolin Weber, San Diego State University
Cassiopeia A in the Cassiopeia constellation is the youngest known neutron star. Based on the observed cooling rate of the star, astrophysicists believe the neutrons in its core to be in a superfluid state. (Top) X-ray image of the Cassiopeia A supernova remnant. (Bottom) Drawing showing the different layers of a neutron star.