The Crescent Nebula
NGC 6888 in Cygnus
also known as Caldwell 27, and Sharpless 105 is an emission nebula, 5000 light-years from Earth. Discovered by William Herschel in 1792, it is formed by the fast stellar winds of a super-hot Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving winds ejected by the star when it became a red giant 250,000 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. This Ha-OIII-RGB data was captured by Pete Proulx.
LARGE
also known as Caldwell 27, and Sharpless 105 is an emission nebula, 5000 light-years from Earth. Discovered by William Herschel in 1792, it is formed by the fast stellar winds of a super-hot Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving winds ejected by the star when it became a red giant 250,000 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. This Ha-OIII-RGB data was captured by Pete Proulx.
LARGE