Royal Astronomical Society Press Release
RAS PN 10/24 (NAM 20) 16-Apr-2010
Observations of how the youngest-known neutron star has cooled over the past decade are giving astronomers new insights into the interior of these super-dense dead stars.
Dr Ho, of the University of Southampton, and Dr Craig Heinke, of the University of Alberta in Canada, measured the temperature of the neutron star in the Cassiopeia A supernova remnant using data obtained by NASA’s Chandra X-ray Observatory between 2000 and 2009.
“This is the first time that astronomers have been able to watch a young neutron star cool steadily over time. Chandra has given us a snapshot of the temperature roughly every two years for the past decade and we have seen the temperature drop during that time by about 3%,” said Dr Ho.
Neutron stars are composed mostly of neutrons crushed together by gravity, compressed to over a million million times the density of lead. They are the dense cores of massive stars that have run out of nuclear fuel and collapsed in supernova explosions. The Cassiopeia A supernova explosion, likely to have taken place around 1680, would have heated the neutron star to temperatures of billions of degrees, from which it has cooled down to a temperature of about two million degrees Celsius.
Chandra: Cassiopeia A: Carbon Atmosphere Discovered On Neutron Star
(X-ray: NASA/CXC/Southampton/W. Ho et al; Illustration: NASA/CXC/M.Weiss)