Mu Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 21h 44m 08.57767s[1]
Declination 28° 44′ 33.4567″[1]
Apparent magnitude (V) 4.49[2]
Characteristics
Spectral type F6V + G2V[3]
B−V color index +0.512±0.007[2]
Astrometry
Radial velocity (Rv)+16.95[4] km/s
Proper motion (μ) RA: +257.012[1] mas/yr
Dec.: −239.009[1] mas/yr
Parallax (π)45.2207 ± 0.2383 mas[1]
Distance72.1 ± 0.4 ly
(22.1 ± 0.1 pc)
Absolute magnitude (MV)2.75[2]
μ1 Cyg
Absolute magnitude (MV)2.77[5]
Absolute bolometric
magnitude (Mbol)		2.91±0.06[6]
μ2 Cyg
Absolute magnitude (MV)4.38[5]
Absolute bolometric
magnitude (Mbol)		4.32±0.06[6]
Orbit[7]
Period (P)789 yr
Semi-major axis (a)5.32″
Eccentricity (e)0.66
Inclination (i)75.5°
Longitude of the node (Ω)110.1°
Periastron epoch (T)1958.0
Argument of periastron (ω)
(secondary)		145.7°
Details[5]
μ1 Cyg
Mass1.31 M☉
Radius1.88±0.07[6] R☉
Luminosity6.0 L☉
Surface gravity (log g)3.93 cgs
Temperature6,354 K
Metallicity [Fe/H]−0.16 dex
Rotational velocity (v sin i)11.6 km/s
Age3.46 Gyr
μ2 Cyg
Mass0.99 M☉
Radius1.08±0.05 R☉
Luminosity1.4 L☉
Surface gravity (log g)4.33 cgs
Temperature5.998 K
Metallicity [Fe/H]−0.24 dex
Rotational velocity (v sin i)6.4 km/s
Age7.11[5] Gyr
Other designations
78 Cyg, BD+28°4169, HIP 107310, CCDM J21442+2845AB, WDS J21441+2845AB[8]
μ1 Cyg: HD 206826, HR 8309, SAO 89940[9]
μ2 Cyg: HD 206827, HR 8310, SAO 89939[10]
Database references
SIMBADμ Cyg
μ1 Cyg
μ2 Cyg

μ Cygni, Latinised as Mu Cygni, is a binary star[11] system in the northern constellation of Cygnus. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.49.[2] The system is located 72 light years distant from the Sun, based on parallax,[1] and is drifting further away with a radial velocity of +17 km/s.[4]

The pair have an orbital period of around 800 years, with a semimajor axis of 5″ and an eccentricity around 0.6.[12] The primary,[9] with an apparent magnitude of 4.69, is an F-type main-sequence star with a stellar classification of F6V.[3] It has 35% more mass than the Sun and 188% of the Sun's radius.[6] The star is spinning with a projected rotational velocity of 9.6 km/s. The secondary companion,[10] with an apparent magnitude of 6.12, is a G-type main-sequence star with a class of G2V.[3] It has a similar radius as the Sun and slightly more mass.[6]

Two reported additional components, C (apparent magnitude 12.93) and D (apparent magnitude 6.94), are believed to be optical doubles rather than part of the Mu Cygni system.[3] Component D is the more distant spectroscopic binary HD 206874 (HIP 107326), consisting of two early F-type subgiants.[13]

References

  1. 1 2 3 4 5 6 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. 1 2 3 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.
  3. 1 2 3 4 Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920 Vizier catalog entry
  4. 1 2 Maldonado, J.; Martínez-Arnáiz, R. M.; Eiroa, C.; Montes, D.; Montesinos, B. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics, 521: A12, arXiv:1007.1132, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948, S2CID 119209183
  5. 1 2 3 4 Luck, R. Earle (2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 21. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744.
  6. 1 2 3 4 5 Fuhrmann, Klaus (2011). "Nearby stars of the Galactic disc and halo - V". Monthly Notices of the Royal Astronomical Society. 414 (4): 2893–2922. Bibcode:2011MNRAS.414.2893F. doi:10.1111/j.1365-2966.2011.18476.x.
  7. ↑ Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
  8. ↑ "CCDM J21442+2845AB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-04-08.
  9. 1 2 "HR 8309". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 January 2014.
  10. 1 2 "HR 8310". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 January 2014.
  11. ↑ 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. S2CID 14878976. Vizier catalog entry
  12. ↑ Malkov, O. Yu.; et al. (October 2012), "Dynamical masses of a selected sample of orbital binaries", Astronomy & Astrophysics, 546 (A69): A69, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774 Vizier catalog entry
  13. ↑ Abt, Helmut A (2009). "MK Classifications of Spectroscopic Binaries". The Astrophysical Journal Supplement. 180 (1): 117–118. Bibcode:2009ApJS..180..117A. doi:10.1088/0067-0049/180/1/117. S2CID 122811461.
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