S Andromeda
On August 17th
1885 the French astronomer Prof L. Gully at Rouen in France saw a star near the
centre of the Andromeda galaxy, it just about reached naked eye brightness it
could just be seen without binoculars or telescopes, but this was no ordinary
star, this was a supernova. A supernova
is a star that destroys itself in a massive explosion.
The star was
designated as S Andromeda, at this time astronomers did not know how far away
the Andromeda Spiral as it was then called was away from the Sun. It was
assumed to be a spiral group of stars within our galaxy. Therefore they could
not work out how bright the star had really become. S Andromeda was in fact the
first extra galactic supernova to have been discovered.
At this time
stars that suddenly appeared in the sky were referred to as nova or ‘new stars’
(nova means new in Latin), but S Andromeda was different and although the astronomers
at the time did not know it,but this was a special nova, a ‘supernova’, although
the term would not be introduced until the 1930s.
When later
the distance to the Andromeda Galaxy as we now call it was worked out, the
modern estimate is about 2.2 million light years we know that S Andromeda
was about 1.6 billion times brighter than the Sun.
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