IC 5146

IC 5146
Amateur image of IC 5146 "Cocoon Nebula"
Observation data
Type	reflection/emission nebula
Right ascension	21h 53m 28.7s
Declination	+47° 16′ 01″
Distance	3300 ly
Apparent magnitude (V)	+7.2
Apparent dimensions (V)	12′
Constellation	Cygnus
Physical characteristics
Other designations	Cocoon Nebula, Caldwell 19, Sh 2-125
See also: Diffuse nebula, Lists of nebulae
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IC 5146 (also Caldwell 19, Sh 2-125, and the Cocoon Nebula) is a reflection^[1]/emission^[2] nebula and Caldwell object in the constellation Cygnus. IC 5146 refers specifically to the star cluster and Sh2-125 to the nebula.^[3] It shines at magnitude +10.0^[4]/+9.3^[2]/+7.2.^[5] Its celestial coordinates are RA 21^h 53.5^m, dec+47° 16′. It is located near the naked-eye star Pi Cygni, the open cluster NGC 7209 in Lacerta, and the bright open cluster M39.^[1][4] The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago;^[6] the nebula is about 12 arcmins across, which is equivalent to a span of 15 light years.^[5] When viewing IC 5146, dark nebula Barnard 168 (B168) is an inseparable part of the experience, forming a dark lane that surrounds the cluster and projects westward forming the appearance of a trail behind the Cocoon.

References

1. ^ ^{a b} Eicher, David J. (1988). The Universe from Your Backyard: A Guide to Deep-Sky Objects from Astronomy Magazine. AstroMedia (Kalmbach Publishing Company). ISBN 0-521-36299-7. 
2. ^ ^{a b} Sanqunetti, Doug (2007). "IC 5146 - Cocoon Nebula". dougsastro.net. http://dougsastro.net/IC-Catalog/ic5146.php. Retrieved 2008-08-06. 
3. ^ http://galaxymap.org/cgi-bin/sharpless.py?s=125
4. ^ ^{a b} Pasachoff, Jay M. (2000). "Atlas of the Sky". Stars and Planets. New York, NY: Peterson Field Guides. pp. 578 pg. ISBN 0-395-93432-X. 
5. ^ ^{a b} Cannistra, Steve (2004). "Cocoon Nebula". starrywonders.com. http://www.starrywonders.com/cocoon.html. Retrieved 2008-08-06. 
6. ^ Nemiroff, Robert; Bonnell, Jerry (2002-10-14). "APOD: 2002 October 14 - IC 5146: The Cocoon Nebula". APOD (NASA). http://apod.nasa.gov/apod/ap021014.html. Retrieved 2008-08-06. 

External links

• SEDS – IC 5146
• Simbad – IC 5146
• NED – IC 5146
• IC5146
• Sharpless Catalog 125
• IC 5146 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Coordinates: 21^h 53^m 32^s, +47° 16′ 06″