Crescent Nebula

Crescent Nebula
Observation data: J2000.0 epoch
Type	Emission
Right ascension	20h 12m 7s[1]
Declination	+38° 21.3′[1]
Distance	5,000 ly
Apparent magnitude (V)	+7.4
Apparent dimensions (V)	18′ × 12′
Constellation	Cygnus
Physical characteristics
Radius	-
Absolute magnitude (V)	-
Notable features	-
Other designations	NGC 6888,[1] Sharpless 105, Caldwell 27
See also: Diffuse nebula, Lists of nebulae
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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. 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 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.

Image Only

• Image by Daniel Lopez large image of whole nebula

Whole Nebula image with explanation

• APOD (2007-11-11) – NASA Astro Picture of the Day: Image by Franck Bugnet

Image with explanation of cause of features of image

• NOAO image

Image of detail of Nebula with text

• Chandra image

detail of nebula

B.D.Moore and J.J.Hester-Hubble space telescope retrieved 20/09/2011

See also

• Cygnus Bubble

References

1. ^ ^{a b c} "SIMBAD Astronomical Database". Results for NGC 6888. http://simbad.u-strasbg.fr/Simbad. Retrieved 2007-04-23. 

External links

• Sharpless Catalog 105
• Crescent Nebula on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images