IC 5146

IC 5146
Reflection nebula
emission nebula
Optical image of IC 5146
Observation data: J2000 epoch
Right ascension21h 53m 28.7s
Declination+47° 16′ 01″
Distance2500±100[1] ly   (780±30 pc)
Apparent magnitude (V)+7.2
Apparent dimensions (V)12
ConstellationCygnus
Physical characteristics
Radius7.5 ly
DesignationsCocoon Nebula, Caldwell 19, Sh 2-125, Cr 470
See also: Lists of nebulae

IC 5146 (also Caldwell 19, Sh 2-125, Barnard 168, and the Cocoon Nebula) is a reflection[2]/emission[3] nebula and Caldwell object in the constellation Cygnus. The NGC description refers to IC 5146 as a cluster of 9.5 mag stars involved in a bright and dark nebula. The cluster is also known as Collinder 470.[4] It shines at magnitude +10.0[5]/+9.3[3]/+7.2.[6] Its celestial coordinates are RA 21h 53.5m , 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.[2][5] The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago;[7] the nebula is about 12 arcmins across, which is equivalent to a span of 15 light years.[6]

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.

  1. ^ Kuhn, Michael A.; Hillenbrand, Lynne A.; Sills, Alison; Feigelson, Eric D.; Getman, Konstantin V. (2018). "Kinematics in Young Star Clusters and Associations with Gaia DR2". The Astrophysical Journal. 870 (1): 32. arXiv:1807.02115. Bibcode:2019ApJ...870...32K. doi:10.3847/1538-4357/aaef8c. S2CID 119328315.
  2. ^ 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.
  3. ^ a b Sanqunetti, Doug (2007). "IC 5146 - Cocoon Nebula". dougsastro.net. Retrieved 2008-08-06.[permanent dead link]
  4. ^ O'Meara, Stephen James: The Caldwell Objects, Sky Publishing Corporation ISBN 0-933346-97-2 page 80
  5. ^ a b Pasachoff, Jay M. (2000). "Atlas of the Sky". Stars and Planets. New York, NY: Peterson Field Guides. p. 578. ISBN 0-395-93432-X.
  6. ^ a b Cannistra, Steve (2004). "Cocoon Nebula". starrywonders.com. Retrieved 2008-08-06.
  7. ^ Nemiroff, R.; Bonnell, J., eds. (2002-10-14). "IC 5146: The Cocoon Nebula". Astronomy Picture of the Day. NASA. Retrieved 2008-08-06.