H/T Lana Duze What caused the Crescent Nebula? Looking like an emerging space cocoon, the Crescent Nebula, visible in the center of the above image, was created by the brightest star in its center. A leading progenitor hypothesis has the Crescent Nebula beginning to form about 250,000 years ago. At that time, the massive central star had evolved to become a Wolf-Rayet star (WR 136), shedding its outer envelope in a strong stellar wind, ejecting the equivalent of our Suns mass every 10,000 years. This wind impacted surrounding gas left over from a previous phase, compacting it into a series of complex shells, and lighting it up. The Crescent Nebula, also known as NGC 6888, lies about 4,700 light-years away in the constellation of Cygnus. Star WR 136 will probably undergo a supernova explosion sometime in the next million years. How it was. After only 4.5 million years (one-thousandth the age of the Sun), HD 192163 began its headlong rush toward a supernova catastrophe. First it expanded enormously to become a red giant and ejected its outer layers at about 20,000 miles per hour. Two hundred thousand years later - a blink of the eye in the life of a normal star - the intense radiation from the exposed hot, inner layer of the star began pushing gas away at speeds in excess of 3 million miles per hour!
Posted on: Wed, 02 Jul 2014 01:30:52 +0000
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