Omega2 Cygni

Omega2 Cygni, Latinized from ω2 Cygni, is the Bayer designation for a solitary[7] 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]

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]
Characteristics
Spectral type M2 III[3]
Astrometry
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
Distance399 ± 9 ly
(122 ± 3 pc)
Absolute magnitude (MV)+0.00[4]
Details
Luminosity301[5] L☉
Temperature3,847[5] K
Other designations
ω2 Cyg, 46 Cygni, BD+48° 3154, HD 195774, HIP 101243, HR 7851, SAO 49741.[6]
Database references
SIMBADdata

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.[8] There is a 58.3% chance that this star is a member of the Hercules stream.[2]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. 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, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  3. 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. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  5. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  6. "ome02 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-22.
  7. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  8. Percy, John R.; Fleming, David E. B. (February 1992), "A photometric survey of suspected small-amplitude red variables", Publications of the Astronomical Society of the Pacific, 104: 96–100, Bibcode:1992PASP..104...96P, doi:10.1086/132963.
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