IC 5146

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IC 5146
Reflection nebula
emission nebula
Ic5146s.jpg
Optical image of IC 5146
Observation data: J2000 epoch
Right ascension 21h 53m 28.7s
Declination +47° 16′ 01″
Distance2500±100 [1]   ly    (780±30  pc)
Apparent magnitude (V)+7.2
Apparent dimensions (V)12′
Constellation Cygnus
Physical characteristics
Radius 7.5 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]

Contents

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.

Young Stellar Objects

View of the IC 5146 star-forming region from ESA's Herschel Space Telescope IC 5146 from Herschel.jpg
View of the IC 5146 star-forming region from ESA's Herschel Space Telescope

IC 5146 is a stellar nursery where star-formation is ongoing. Observations by both the Spitzer Space Telescope and the Chandra X-ray Observatory have collectively identified hundreds of young stellar objects. [8] [9] Young stars are seen in both the emission nebula, where gas has been ionized by massive young stars, and in the infrared-dark molecular cloud that forms the "tail". One of the most massive stars in the region is BD +46 3474, a star of class B1 that is an estimated 14±4 times the mass of the sun. [10]

Another interesting star in the nebula is BD +46 3471, which is an example of a HAeBe star, an intermediate mass star with strong emission lines in its spectrum. [11]

References

  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. 1 2 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. 1 2 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. 1 2 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. 1 2 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.
  8. ↑ Harvey, Paul M.; Huard, Tracy L.; Jørgensen, Jes K.; Gutermuth, Robert A.; Mamajek, Eric E.; Bourke, Tyler L.; Merín, Bruno; Cieza, Lucas; Brooke, Tim; Chapman, Nicholas; Alcalá, Juan M.; Allen, Lori E.; Evans II, Neal J.; Di Francesco, James; Kirk, Jason M. (2008). "TheSpitzerSurvey of Interstellar Clouds in the Gould Belt. I. IC 5146 Observed With IRAC and MIPS". The Astrophysical Journal. 680 (1): 495–516. Bibcode:2008ApJ...680..495H. doi: 10.1086/587687 . ISSN   0004-637X.
  9. ↑ Getman, Konstantin V.; Broos, Patrick S.; Kuhn, Michael A.; Feigelson, Eric D.; Richert, Alexander J. W.; Ota, Yosuke; Bate, Matthew R.; Garmire, Gordon P. (2017). "Star Formation In Nearby Clouds (SFiNCs): X-Ray and Infrared Source Catalogs and Membership". The Astrophysical Journal Supplement Series. 229 (2): 28. arXiv: 1612.05282 . Bibcode:2017ApJS..229...28G. doi: 10.3847/1538-4365/229/2/28 . ISSN   1538-4365. S2CID   59124520.
  10. ↑ Weidner, Carsten; Kroupa, Pavel (2006). "The maximum stellar mass, star-cluster formation and composite stellar populations". Monthly Notices of the Royal Astronomical Society. 365 (4): 1333–1347. arXiv: astro-ph/0511331 . Bibcode:2006MNRAS.365.1333W. doi: 10.1111/j.1365-2966.2005.09824.x . ISSN   0035-8711. S2CID   11688023.
  11. ↑ Reipurth, Bo (2008). Handbook of star forming regions. San Francisco: Astronomical Society of the Pacific. ISBN   978-1-58381-670-7.


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