Omega2 Cygni

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For other star systems with this Bayer designation, see ω Cygni.
Omega2 Cygni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cygnus
Right ascension 20h 31m 18.81663s[1]
Declination +49° 13′ 13.0656″[1]
Apparent magnitude (V) 5.5292±0.0013[2]
Spectral type M2 III[3]
Radial velocity (Rv) −64.15±0.20[2] km/s
Proper motion (μ) RA: +9.21[1] mas/yr
Dec.: −31.88[1] mas/yr
Parallax (π) 8.17 ± 0.19[1] mas
Distance 399 ± 9 ly
(122 ± 3 pc)
Luminosity 301[4] L
Temperature 3,847[4] K
Other designations
ω2 Cyg, 46 Cygni, BD+48° 3154, HD 195774, HIP 101243, HR 7851, SAO 49741.[5]
Database references

Omega2 Cygni2 Cyg, ω2 Cygni) is the Bayer designation for a solitary[6] star in the northern constellation of Cygnus. It has an apparent visual magnitude of 5.5,[2] which is faintly visible to the naked eye on a dark night. Based upon an annual parallax shift of 8.17 mas,[1] it is located roughly 399 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.08 due to interstellar dust.[2]

This is a red giant star on the asymptotic giant branch, with a stellar classification of M2 III.[3] It is a suspected variable star, although the evidence is considered "doubtful or erroneous". If it does exist, the variability is small with an amplitude of 0.05 magnitude and a timescale of around 30 days.[7] There is a 58.3% chance that this star is a member of the Hercules stream.[2]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, Bibcode:2005A&A...430..165F, arXiv:astro-ph/0409579Freely accessible, doi:10.1051/0004-6361:20041272. 
  3. ^ a b Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239. 
  4. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  5. ^ "ome02 Cyg -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-02-22. 
  6. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  7. ^ Percy, John R.; Fleming, David E. B. (February 1992), "A photometric survey of suspected small-amplitude red variables", Astronomical Society of the Pacific, Publications, 104: 96−100, Bibcode:1992PASP..104...96P, doi:10.1086/132963.