The supernova remnant 3C 58 contains a spinning neutron star, known as PSR J0205+6449, at its center. Astronomers studied this neutron star and others like it to probe the nature of matter inside these very dense objects. A new study, made using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton, reveals that the interiors of neutron stars may contain a type of ultra-dense matter not found anywhere else in the Universe. In this image of 3C 58, low-energy X-rays are colored red, medium-energy X-rays are green, and the high-energy band of X-rays is shown in blue. The X-ray data have been comb…