Editor's Note: this is a variant of this composite image: www.flickr.com/photos/28634332@N05/5474156466/, showing Cas A in all its glory minus the illustration inset.
This composite image shows a beautiful X-ray and optical view of Cassiopeia A (Cas A), a supernova remnant located in our Galaxy about 11,000 light years away. These are the remains of a massive star that exploded about 330 years ago, as measured in Earth's time frame. X-rays from Chandra are shown in red, green and blue along with optical data from Hubble in gold.
At the center of the image is a neutron star, an ultra-dense star created by the supernova. Ten years of observations with Chandra have revealed a 4% decline in the temperature of this neutron star, an unexpectedly rapid cooling. 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.
This new research has allowed the teams to place the first observational constraints on a range of properties of superfluid material in neutron stars. The critical temperature was constrained to between one half a billion to just under a billion degrees Celsius. A wide region of the neutron star is expected to be forming a neutron superfluid as observed now, and to fully explain the rapid cooling, the protons in the neutron star must have formed a superfluid even earlier after the explosion. Because they are charged particles, the protons also form a superconductor.
Using a model that has been constrained by the Chandra observations, the future behavior of the neutron star has been predicted . The rapid cooling is expected to continue for a few decades and then it should slow down.
Credit: X-ray: NASA/CXC/xx; Optical: NASA/STScI; Illustration: NASA/CXC/M.Weiss
Read entire caption/view more images: chandra.harvard.edu/photo/2011/casa/
Caption credit: Harvard-Smithsonian Center for Astrophysics
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p.s. You can see all of our Chandra photos in the Chandra Group in Flickr at: www.flickr.com/groups/chandranasa/ We'd love to have you as a member!