NGC 6888 - The Crescent Nebula

NGC 6888 - The Crescent Nebula

NGC 6888 (Caldwell 27) - The Crescent Nebula is an emission nebula located in the constellation Cygnus at a distance of approximately 5000 light years.  Like The Bubble Nebula it is formed from the fast stellar wind of a Wolf Rayet star, WR 136 (HD 192163) - the bright star near the center of the shell.   A Wolf Rayet star is one that rapidly expels a large amount of its mass in the form of a strong stellar wind.   This stellar wind collides with surrounding molecular clouds (also emitted from this same star during an earlier red giant phase) resulting in a shell formation.   This nebula is located along a very dense region of the summer Milky Way which explains the numerous stars in the surrounding field.

The above image is a 6.5-hour color composite from a 110-minute Hydrogen Alpha-filtered image and red, green, and blue-filtered exposures (88, 120, 60 minutes) captured using a William Optics FLT110 4.3" f/7 refractor with an SXV-H9 CCD camera during the evenings of 20-24 September 2008.

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