Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  Crescent Nebula  ·  HD192003  ·  HD192020  ·  HD192163  ·  HD192182  ·  HD192303  ·  HD192361  ·  HD192444  ·  HD192537  ·  HD228152  ·  HD228153  ·  HD228185  ·  HD228243  ·  HD228304  ·  HD228324  ·  HD228376  ·  HD228409  ·  HD228410  ·  HD228411  ·  HD228424  ·  LBN 203  ·  NGC 6888  ·  Sh2-105
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NGC6888 The Crescent Nebula, Dale A Chamberlain
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Getting plate-solving status, please wait...
NGC6888 The Crescent Nebula, Dale A Chamberlain
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Description

The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures.

The star is shedding its outer envelope in a strong stellar wind, ejecting the equivalent of the Sun's mass every 10,000 years. The nebula's complex structures are likely the result of this strong wind interacting with material ejected in an earlier phase. Burning fuel at a prodigious rate and near the end of its stellar life this star should ultimately go out with a bang in a spectacular supernova explosion.

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