59 Cygni

59 Cygni is a multiple[7] star system in the northern constellation of Cygnus, located roughly 1,300 light years away from Earth. It is visible to the naked eye as a blue-white hued star with a combined apparent visual magnitude of 4.74.[3]

This article is about f1 Cygni. For other stars with this Bayer designation, see f Cygni.
59 Cygni

A visual band light curve of V832 Cygni. The main plot shows the long-term variability, and the inset plot shows the variation over a single orbital period. Adapted from Harmanec et al. (2002)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 59m 49.55164s[2]
Declination +47° 31′ 15.3789″[2]
Apparent magnitude (V) 4.74[3]
Characteristics
Spectral type B1.5Vnne[4] + sdO + A3V + A8III + ?[5]
B−V color index −0.084±0.004[3]
Variable type γ Cas[6]
Astrometry
Radial velocity (Rv)1.4±4.2[3] km/s
Proper motion (μ) RA: +9.534[2] mas/yr
Dec.: +3.090[2] mas/yr
Parallax (π)2.5088 ± 0.3226 mas[2]
Distanceapprox. 1,300 ly
(approx. 400 pc)
Absolute magnitude (MV)−3.37[3]
Orbit[7]
Period (P)28.1871±0.0011 d
Eccentricity (e)0.141±0.008
Periastron epoch (T)45677.6±0.3 HJD
Argument of periastron (ω)
(secondary)		257±4°
Semi-amplitude (K1)
(primary)		11.7±0.9 km/s
Semi-amplitude (K2)
(secondary)		121.3±1.1 km/s
Details[7]
59 Cyg Aa – Be star
Mass6.3–9.4 M☉
Radius5.5–7.0 R☉
Luminosity7,943 L☉
Surface gravity (log g)3.78±0.09 cgs
Temperature21,800±700 K
Rotational velocity (v sin i)379±27 km/s
59 Cyg Aa – sdO
Mass0.62–0.91 M☉
Radius0.34–0.43 R☉
Luminosity1,000 L☉
Surface gravity (log g)5.0±1.0 cgs
Temperature52,100±4,800 K
Rotational velocity (v sin i)< 40 km/s
Other designations
f1 Cyg, 59 Cyg, V832 Cyg, BD+46°3133, FK5 1551, HD 200120, HIP 103632, HR 8047, SAO 50335, WDS J20598+4731[8]
Database references
SIMBADdata

The primary component and brightest member of this system, designated 59 Cyg Aa, is a rapidly rotating Be star with a stellar classification of B1.5 Vnne.[4] This is a well-studied star thanks to pronounced spectral variations that have been observed since 1916, and two short-term shell star phases that were observed in 1973 and 1974–5.[9] It is actually a confirmed spectroscopic binary system with a high temperature subdwarf O-type companion in a 28-day orbital period. The latter is heating the nearest side of the circumstellar gaseous disk that surrounds the primary.[7]

Orbiting the primary pair is 59 Cyg Ab, a magnitude 7.64 A-type main-sequence star of class A3V, located at an angular separation of 0.200″. A fourth component is a magnitude 9.8 A-type giant star of class A8III at a separation of 20.2″ along a position angle (PA) of 352°, as of 2008. The fifth companion is magnitude 11.7 at a separation of 26.7″ and a PA of 141°.[5] Gaia Data Release 2 suggests that the companions at 20.2″ and 26.7″ are respectively 382 pc and 366 pc away and moving in approximately the same direction as the primary triple.[10][11]

References
  1. Harmanec, P.; Božić, H.; Percy, J. R.; Yang, S.; Ruždjak, D.; Sudar, D.; Wolf, M.; Iliev, L.; Huang, L.; Buil, C.; Eenens, P. (May 2002). "Properties and nature of Be stars". Astronomy & Astrophysics. 387 (2): 580–594. Bibcode:2002A&A...387..580H. doi:10.1051/0004-6361:20020453.
  2. 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.
  3. 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.
  4. Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179.
  5. 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.
  6. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. Peters, Geraldine J.; et al. (March 2013), "Far-ultraviolet Detection of the Suspected Subdwarf Companion to the Be Star 59 Cygni", The Astrophysical Journal, 765 (1): 8, arXiv:1301.0257, Bibcode:2013ApJ...765....2P, doi:10.1088/0004-637X/765/1/2, S2CID 118450084, 2.
  8. "59 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-17.
  9. Harmanec, P.; et al. (May 2002), "Properties and nature of Be stars. XXI. The long-term and the orbital variations of V832 Cyg = 59 Cyg", Astronomy and Astrophysics, 387 (2): 580–594, Bibcode:2002A&A...387..580H, doi:10.1051/0004-6361:20020453.
  10. 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.
  11. 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.
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