Crescent Nebula
This articleneeds additional citations forverification.(May 2024) |
Emission nebula | |
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![]() The Crescent Nebula, as taken by anamateur astronomer | |
Observation data: J2000.0epoch | |
Right ascension | 20h12m7s[1] |
Declination | +38° 21.3′[1] |
Distance | 5,000ly |
Apparent magnitude(V) | +7.4 |
Apparent dimensions (V) | 18′ × 12′ |
Constellation | Cygnus |
Designations | NGC6888,[1]Sharpless105,Caldwell27 |
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/C27_-_Crescent_Nebula.jpg/302px-C27_-_Crescent_Nebula.jpg)
TheCrescent Nebula(also known asNGC 6888,Caldwell 27,Sharpless 105) is anemission nebulain the constellationCygnus,about 5000light-yearsaway fromEarth.It was discovered byWilliam Herschelin 1792.[2]It is formed by the faststellar windfrom theWolf-Rayet starWR 136(HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became ared giantaround 250,000[3]to 400,000[citation needed]years ago. The result of the collision is a shell and twoshock waves,one moving outward and one moving inward. The inward moving shock wave heats the stellar wind toX-ray-emitting temperatures.
The Crescent Nebula is a rather small object located about 2 degrees Southwest ofSadr.While considered bright by astronomical imaging standards, visually it is relatively faint. For most telescopes it requires aUHC or OIII filterto see. Under favorable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or aEurosign shape which makes some to call it the "Euro sign nebula".
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NGC 6888 in Hydrogen and Oxygen Light. HOO Palette. Imaged by Don Christopher Deaver
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Crescent Nebula in H-alpha and OIII. Imaged with a 715mm focal length telescope. The hydrogen gas is red. The oxygen is blue.
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Image ofNGC 6888using H-alpha filter.
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Picture ofNGC 6888captured in narrowband by amateur astronomer Luca Moretti
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NGC 6888 imaged in 3 nm hydrogen-alpha and oxygen-III narrowband at 2800mm focal length by amateur astronomer Patrick Hsieh.
See also
[edit]References
[edit]- ^abc"NGC 6888".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2007-04-23.
- ^Erdmann, Robert."NGC 6888".The NGC/IC Project.Archived fromthe originalon 2012-05-20.
- ^"WR 136".jumk.de.Retrieved25 March2018.
External links
[edit]![](https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
- "Crescent".National Optical Astronomy Observatory. Archived fromthe originalon 2007-08-30.Retrieved2005-01-08.
- "Crescent Nebula: Live Fast, Blow Hard and Die Young".Chandra X-Ray Observatory. 14 October 2003.
- Crescent Nebula onWikiSky:DSS2,SDSS,GALEX,IRAS,Hydrogen α,X-Ray,Astrophoto,Sky Map,Articles and images
- Nemiroff, R.; Bonnell, J., eds. (11 November 2007)."NGC 6888: The Crescent Nebula".Astronomy Picture of the Day.NASA.Retrieved25 March2018.