Thursday, January 19, 2012

Crescent nebula

The story of a Wolf-Rayet star

       These special massive stars (>30 times the solar mass) are in their later stage of evolution, about to become a supernova. Due to the fact that for a few thousand years in this period they lose a lot of mass through stellar winds, more than half of the known WR stars are surrounded by nebulae.

       Crescent is one of these nebulae, a supernova cocoon where a lot happens. It's 4700 light years away (!), measuring about 20 light years across. The star creating this object, WR 136 ( or HD 192163) is a member of the Cygnus OB1 association, a cluster of young stars in that constellation.

    Wondering why I said that this star is nearing the end of it's life while being part of a young cluster of stars? The answer lies in the amazing fact that the more massive a star is, the less time it will live! This way, a 0.1 solar mass star can fuse nuclei together for even 1000 billion years while one as massive as 100 suns will destroy itself in only a few hundred thousand years, a blink of an (cosmic) eye!

Behold, NGC 6888:

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