68 Cygni information

68 Cygni
	Location of 68 Cygni (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Cygnus
Right ascension	21h 18m 27.18561s
Declination	+43° 56′ 45.4070″
Apparent magnitude (V)	5.00
Characteristics
Spectral type	O7.5IIIn((f))
U−B color index	−0.94
B−V color index	−0.01
Variable type	ELL
Astrometry
Radial velocity (Rv)	1 ± 5 km/s
Proper motion (μ)	RA: 4.85 ± 0.22 mas/yr ; Dec.: −8.40 ± 0.20 mas/yr
Parallax (π)	0.70 ± 0.23 mas
Distance	approx. 5,000 ly ; (approx. 1,400 pc)
Absolute magnitude (MV)	approx. −6.70
Details
Mass	23–51 M☉
Surface gravity (log g)	3.6 cgs
Temperature	34,000 K
Rotational velocity (v sin i)	399 km/s
Other designations
	V1809 Cygni, A Cygni, HD 203064, HR 8154, BD+43 3877, HIP 105186, WDS J21185+4357
Database references
SIMBAD	data

68 Cygni is the Flamsteed designation for a star in the constellation Cygnus. Located approximately 1,400 parsecs (4,600 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.

^ ^a ^b ^c ^d ^e 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. Vizier catalog entry
^ ^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
^ 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.
^ ^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.
^ 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.
^ Wilson, R. A. (1953). "General catalogue of stellar radial velocities". Washington. Carnegie Institution of Washington: 0. Bibcode:1953GCRV..C......0W. Vizier catalog entry
^ Ducati, J. R.; Penteado, E. M.; Turcati, R. (2010). "The mass ratio and initial mass functions in spectroscopic binaries" (PDF). Astronomy & Astrophysics. 525: A26. Bibcode:2011A&A...525A..26D. doi:10.1051/0004-6361/200913895.
^ Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiant". Astronomische Nachrichten. 331 (4): 349–361. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483. Vizier catalog entry
^ ^a ^b 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.

Cite error: There are <ref group=n> tags on this page, but the references will not show without a {{reflist|group=n}} template (see the help page).

[van_Leeuwen2007-1] 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. Vizier catalog entry

[Ducati_2002-2] 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

[sota-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.

[herrero-4] 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.

[Esipov-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.

[Wilson_1953-7] Wilson, R. A. (1953). "General catalogue of stellar radial velocities". Washington. Carnegie Institution of Washington: 0. Bibcode:1953GCRV..C......0W. Vizier catalog entry

[Ducati-8] Ducati, J. R.; Penteado, E. M.; Turcati, R. (2010). "The mass ratio and initial mass functions in spectroscopic binaries" (PDF). Astronomy & Astrophysics. 525: A26. Bibcode:2011A&A...525A..26D. doi:10.1051/0004-6361/200913895.

[Hohle_2010-9] Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiant". Astronomische Nachrichten. 331 (4): 349–361. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483. Vizier catalog entry

[pastel-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.

Observation data Epoch J2000 Equinox J2000
Location of 68 Cygni (circled)
Constellation	Cygnus
Right ascension	21^h 18^m 27.18561^s^[1]
Declination	+43° 56′ 45.4070″^[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 (R_v)	1 ± 5^[6] km/s
Proper motion (μ)	RA: 4.85 ± 0.22^[1] mas/yr Dec.: −8.40 ± 0.20^[1] mas/yr
Parallax (π)	0.70 ± 0.23 mas^[1]
Distance	approx. 5,000 ly (approx. 1,400 pc)
Absolute magnitude (M_V)	approx. −6.70

Details

Mass	23^[7]–51^[8] `M`_☉
Surface gravity (log g)	3.6^[9] cgs
Temperature	34,000^[9] 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
SIMBAD	data

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