(Cas A, SNR G111.7-02.1)
(supernova remnant visible for 300 years)
Cassiopeia A (or Cas A) is a supernova remnant about
11000 light-years away, left over from a supernova that would have first
been visible to Earth at some time near 1670-1680;
there are records of observations in that era that may indicate it,
but no unambiguous record of a new source,
and various terms have been used for the supernova,
including SN 1667, SN 1671, and SN 1680.
The remnant was first recorded in 1948 and has been much studied since.
Reflections of the supernova off gas clouds have recently provided
some look at the actual event.
An X-ray source detected by Chandra X-ray Observatory in 1999 is presumed to be
the resulting neutron star.
This supernova was not either of the 1500s/1600s two
that were observed by the naked eye, i.e.,
neither that noted by Tycho Brahe in 1572 in
Cassiopeia (SN 1572 aka Tycho's supernova),
nor that noted by Johannes Kepler in 1604 in
Ophiuchus (SN 1604 aka Kepler's supernova).
| || |
Referenced by page:
supernova remnant (SNR)