Cassiopeia A

Cassiopeia A ( Cas A ) is a supernova remnant in the constellation Cassiopeia in about 11,000 light years away, which has a diameter of about 10 light years.

He is the remnant of a supernova explosion that would have on the earth by the year 1680 can be observed, if she had not taken place behind gas and dust clouds. Perhaps the supernova appeared as a star sixth size, the astronomer John Flamsteed on August 16, 1680 Star cataloged 3 Cassiopeiae, but not since then is found. Today Cassiopeia A is the strongest extrasolar radio source in the sky. The radio source was discovered in 1947, the optical identification succeeded in 1950. Cassiopeia A was the youngest known supernova remnant in our galaxy until the discovery of supernova remnant G1.9 0.3.

Using a light echo, it has been possible to observe the historical supernova spectrally. A light echo is produced by scattering from dust particles of interstellar matter. Since the dust outside the line of sight earth is a supernova, the path is longer and today the explosion flash can be examined. With the help of the MIPS instrument on the Hubble Space Telescope, the infrared spectrum of the supernova could be investigated and therefore belongs to the type IIb. In Cas A is accordingly to the supernova remnant of a core collapse supernova of a former Red About Ries, who has lost his hydrogen-rich atmosphere by stellar wind prior to the explosion.

In observations with the Chandra X-ray telescope a point X-ray source near the center of Cas A = 3C 461 could SNR = G111.7 -2.1 are found. Since neither in the field of X-ray variability of the source could be found in the optical, it is very unlikely that there is a cataclysmic variable in the foreground or an active galactic nucleus in the background of Cas A. The X-ray spectrum is best described as that of a neutron star with a polar spot with a temperature of about 2.8 million Kelvin.