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NGC 346 - Star forming region in the Small Magellanic Cloud
(SMC) |
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Description of
object:
The nebula NGC 346 in
the middle of the picture has a diameter of about 200 light years and is the
biggest and most active star forming region in the Small Magellanic Cloud, a
210.000 light year distant satellite galaxy of the Milky Way. NGC 371 is
another, weaker star birth region located at the left border of the picture.
The very hot, white-blue stars in the nebula's central part are just a
few million years old and ionize the nebula due to their high UV radiation. NGC
346 (and also NGC 371) shows a green-blue color which is rather untypical for a
star forming region. Because of the extremely high radiant power of the star
cluster also oxygen atoms are being exited to light. Their green-blue light
outshines the otherwise dominant red emission of the H-alpha hydrogen line.
A rare blue star cluster can be seen near the right border of the
image. Such objects are very young compared to the usual billion year's old
globular clusters. Its age is 100 million years at most. It still contains a
lot of short-living hot blue stars because of its young age. Blue globular
clusters need far more interstellar matter for their formation than common
globular clusters. This makes them very rare objects. |
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