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Supernova
1987A
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(Section Not Complete)
In 1987 a supernova
(designated
SN1987A
by astronomers) was observed in a nearby
galaxy called the
Large
Magellanic Cloud.
Detection of the Neutrinos
This was the first "nearby"
supernova in the last 3 centuries, and for the first time astronomers not only
observed
the light show, but also detected 19 of the elusive
neutrinos (the detectors observed electron anti-neutrinos, to be more precise)
produced by the collapse of the star's core. The burst of neutrinos
preceded the first sighting of the supernova's light by about 3 hours, in
agreement with the expectations of
current supernova theory. These observations are rather conclusive evidence for the
correctness of the core collapse mechanism, since it would be difficult to produce
the observed neutrino burst by any other means.
It is estimated that
for an instant in 1987 on the earth
the neutrino luminosity of SN1987A was as large as the
visible-light luminosity of the entire universe.
The Mysterious Rings
The adjacent figure
is a 1994
Hubble Space Telescope
image of the region surrounding
SN1987A. The supernova is in the center. The two bright stars are just in the
field of view and are not associated with the supernova. The bright yellow
ring is thought to be gas and dust heated by the supernova (the expanding shell
of the explosion itself that will produce the supernova remnant
is still too small to be seen in this photograph).
The two large
rings are not yet completely understood, though they appear to be associated
with the supernova. It is rather
certain that the rings result from something that the star did before
it became a supernova, probably associated with the strong stellar winds expected in such stars that emit
large amounts of matter into space. Click here for one of several
ideas about the source of the mysterious rings.
Here is another image of supernova 1987a and the nearby Tarantula Nebula
of the Large Magellanic Cloud.
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