68 Cygni

68 Cygni
Location of 68 Cygni (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 21h 18m 27.18622s[1]
Declination +43° 56′ 45.3992″[1]
Apparent magnitude (V) 5.00[2]
Characteristics
Spectral type O7.5IIIn((f))[3][4]
U−B color index −0.94[2]
B−V color index −0.01[2]
Variable type ELL[5][n 1]
Astrometry
Radial velocity (Rv)1 ± 5[6] km/s
Proper motion (μ) RA: +4.632[1] mas/yr
Dec.: −8.487[1] mas/yr
Parallax (π)1.4498 ± 0.1152 mas[1]
Distance2,200 ± 200 ly
(690 ± 50 pc)
Absolute magnitude (MV)−7.9[7]
Details
Mass23[8] – 36+14
−10[9] M☉
Radius15.7+2.3
−2.0[9] R☉
Luminosity316,000+110,000
−82,000[9] L☉
Surface gravity (log g)3.6+0.09
−0.08[9] cgs
Temperature34,000[10] K
Rotational velocity (v sin i)399[4] km/s
Other designations
V1809 Cygni, A Cygni, HD 203064, HR 8154, BD+43 3877, HIP 105186, WDS J21185+4357
Database references
SIMBADdata

68 Cygni is the Flamsteed designation for a star in the constellation Cygnus. Located approximately 690 parsecs (2,300 ly) distant, the star is a hot blue giant of spectral type O7.5IIIn((f)), a massive star that is likely currently expanding to become a supergiant. The star is surrounded by a ring-shaped nebula (likely a Strömgren sphere) named S 119.

68 Cygni is currently classified as a rotating ellipsoidal variable, varying between apparent magnitudes 4.98 and 5.09, although the classification as a rotating ellipsoidal variable is subject to controversy. Barely visible to the naked eye, the star is likely to have a mass of around 26 solar masses and a temperature of approximately 34,000 kelvins, although many of the star's physical parameters are subject to uncertainties due to the unclear nature of the system.

  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c Ducati, J. R. (2002). "Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D. Vizier catalog entry
  3. ^ Sota, A.; Maíz Apellániz, J.; Walborn, N. R.; Alfaro, E. J.; Barbá, R. H.; Morrell, N. I.; Gamen, R. C.; Arias, J. I. (2011). "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R ~ 2500". The Astrophysical Journal Supplement Series. 193 (2): 24–50. arXiv:1101.4002. Bibcode:2011ApJS..193...24S. doi:10.1088/0067-0049/193/2/24. S2CID 119248206.
  4. ^ a b Simón-Díaz, S.; Herrero, A. (2014). "The IACOB project: I. Rotational velocities in northern Galactic O- and early B-type stars revisited. The impact of other sources of line-broadening". Astronomy & Astrophysics. 562: A135. arXiv:1311.3360. Bibcode:2014A&A...562A.135S. doi:10.1051/0004-6361/201322758. S2CID 119278062.
  5. ^ Esipov, V. F.; Klementeva, A. Y.; Kovalenko, A. V.; Lozinskaya, T. A.; Lyntyj, V. M.; Sitnik, T. G.; Udalstov, V. A. (1982). "The Ring Nebulae around the O-Stars – Observations of S119 and its Central Star 68-CYGNI". Astronomicheskii Zhurnal. 59 (September–October): 965–974. Bibcode:1982AZh....59..965E.
  6. ^ Wilson, R. A. (1953). "General catalogue of stellar radial velocities". Washington. Carnegie Institution of Washington: 0. Bibcode:1953GCRV..C......0W. Vizier catalog entry
  7. ^ Wegner, W. (2003). "The total-to-selective extinction ratio determined from near IR photometry of OB stars". Astronomische Nachrichten. 324 (3): 219. Bibcode:2003AN....324..219W. doi:10.1002/asna.200310081.
  8. ^ Ducati, J. R.; Penteado, E. M.; Turcati, R. (2010). "The mass ratio and initial mass functions in spectroscopic binaries". Astronomy & Astrophysics. 525: A26. Bibcode:2011A&A...525A..26D. doi:10.1051/0004-6361/200913895. hdl:10183/99264.
  9. ^ a b c d Repolust, T.; Puls, J.; Herrero, A. (2004). "Stellar and wind parameters of Galactic O-stars. The influence of line-blocking/blanketing". Astronomy and Astrophysics. 415 (1): 349–376. Bibcode:2004A&A...415..349R. doi:10.1051/0004-6361:20034594.
  10. ^ Soubiran, C.; Le Campion, J. -F.; Cayrel De Strobel, G.; Caillo, A. (2010). "The PASTEL catalogue of stellar parameters". Astronomy and Astrophysics. 515: A111. arXiv:1004.1069. Bibcode:2010A&A...515A.111S. doi:10.1051/0004-6361/201014247. S2CID 118362423.


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