74 Cygni

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74 Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension  21h 36m 56.97051s[1]
Declination +40° 25′ 48.5818″[1]
Apparent magnitude (V) 5.04[2]
Evolutionary stage main sequence[3]
Spectral type A3 Vn[4]
B−V color index 0.198±0.003[2]
Radial velocity (Rv)5.3±2.9 km/s
Proper motion (μ) RA: +2.270[1] mas/yr
Dec.: +18.399[1] mas/yr
Parallax (π)13.0909 ± 0.2893[1] mas
Distance249 ± 6 ly
(76 ± 2 pc)
Absolute magnitude (MV)0.95[2]
Period (P)574.632±9.4158 d
Semi-major axis (a)8.56±0.91 mas
Eccentricity (e)0.5349±0.1066
Inclination (i)102.1±4.39°
Longitude of the node (Ω)18.92°
Periastron epoch (T)8579.5387±18.6175
Argument of periastron (ω)
74 Cyg A
Mass1.68[6] M
Radius1.6[7] R
Luminosity35.64[2] L
Surface gravity (log g)3.89[6] cgs
Temperature7,859±267[6] K
Rotational velocity (v sin i)201[3] km/s
Age606[6] Myr
Other designations
74 Cyg, BD+39°4612, FK5 811, HD 205835, HIP 106711, HR 8266, SAO 51101, WDS J21369+4025[8]
Database references

74 Cygni is a visual binary[9] star system in the northern constellation Cygnus, located around 249 light years distant from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 5.04.[2] The pair orbit each other with a period of 1.57 years and an eccentricity of 0.5.[5] The system is a source of X-ray emission, which is most likely coming from the secondary component.[10]

The primary component is an A-type main-sequence star with a stellar classification of A3 Vn;[4] a star that is fusing its core hydrogen. The 'n' suffix indicates "nebulous" absorption lines due to rapid rotation, with the star having a projected rotational velocity of 201 km/s.[3] The high rate of spin is giving the star an oblate shape with a equatorial bulge that is 8% larger than the polar radius.[11] The star has 1.68[6] times the mass of the Sun and is radiating 36[2] times the Sun's luminosity from its photosphere at an effective temperature of about 7,859 K.[6]


  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d e f 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.
  3. ^ a b c Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  4. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  5. ^ a b ESA (1997), The HIPPARCOS and TYCHO catalogues. Astrometric and photometric star catalogues derived from the ESA HIPPARCOS Space Astrometry Mission, 1200, Bibcode:1997ESASP1200.....E, ISBN 9290923997.
  6. ^ a b c d e f David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  7. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  8. ^ "74 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-20.
  9. ^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  10. ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
  11. ^ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2.