Explanation:
Supernova remnant
Cassiopeia A (Cass A) is a
comfortable
11,000 light-years away.
Light from the Cass A supernova,
the death explosion of a massive star,
first reached Earth just 330 years ago.
The expanding debris cloud spans about 15 light-years in
this composite
X-ray/optical image,
while the bright source near the center is a
neutron star
(inset illustration)
the incredibly dense, collapsed remains of the stellar core.
Still hot enough to emit X-rays, Cass A's neutron star is cooling.
In fact, 10 years of observations with the orbiting
Chandra X-ray observatory find that
the
neutron star is cooling
rapidly, so rapidly that researchers suspect a large part of
the neutron star's core is forming a frictionless
neutron superfluid.
The Chandra results represent the first observational evidence for this
bizarre state of matter.
