The Chandra X-ray Observatory is a satellite launched by NASA on July 23, 1999. Chandra is a space based telescope since the Earth’s atmosphere absorbs the vast majority of X-rays. Chandra is 100 times more sensitive to X-ray sources than previous X-ray telescopes.
Chandra has been observing a supernova remnant called Cassiopeia A for 10 years. This supernova remnant is located approximately 11,000 light years away from Earth. As one might expect it is located in the constellation Cassiopeia. While the supernova occurred 11,000 years ago, its light would have reached earth about 300 years ago. Unfortunately, there are no historical records of anyone observing the supernova.
Scientists believe that the star that exploded into a supernova is now a neutron star. During the time that Cassiopeia A has been under observation, this neutron star has slowly cooled down by about 4%. Why has it cooled down?
Two new papers by independent research teams show that this cooling is likely caused by a neutron superfluid forming in its central regions, the first direct evidence for this bizarre state of matter in the core of a neutron star.
Normally we think of matter as having three states: solid, liquid, and gas. When matter is in a superfluid state, it behaves like a fluid without viscosity and with infinite thermal conductivity. Without friction, a superfluid can easily escape a container it is placed in. In the case of Cassiopeia A, this superfluid is allowing energy to escape the star much more rapidly, and is thus cooling the star.
via : Cassiopeia A: NASA’S Chandra Finds Superfluid in Neutron Star’s Core
