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33 Cygni
Observation data; Epoch J2000 Equinox J2000
Constellation	Cygnus
Right ascension	20h 13m 23.86661s
Declination	+56° 34′ 03.7999″
Apparent magnitude (V)	4.28
Characteristics
Evolutionary stage	main sequence
Spectral type	A3 IV–Vn
B−V color index	0.114±0.001
Astrometry
Radial velocity (Rv)	−16.13±2.53 km/s
Proper motion (μ)	RA: +61.82 mas/yr ; Dec.: +82.18 mas/yr
Parallax (π)	20.48 ± 0.12 mas
Distance	159.3 ± 0.9 ly ; (48.8 ± 0.3 pc)
Absolute magnitude (MV)	0.84
Details
Mass	2.33±0.01 M☉
Radius	2.76 R☉
Luminosity	44.3±1.0 L☉
Temperature	8,395+97; −96 K
Rotational velocity (v sin i)	243 km/s
Age	400 Myr
Other designations
	33 Cyg, BD+56°2376, FK5 758, HD 192696, HIP 99655, HR 7740, SAO 32378, WDS J20145+3648A
Database references
SIMBAD	data

33 Cygni is a single^[7] star located 159 light years away in the northern constellation Cygnus. It is visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.28.^[2] The star is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.^[5] Eggen (1995) listed it as a proper motion candidate for membership in the IC 2391 supercluster.^[9]

This star has a stellar classification of A3 IV–Vn,^[4] showing a spectrum with traits intermediate between an A-type main-sequence star and an evolving subgiant star. The 'n' suffix indicates "nebulous" absorption lines due to rapid rotation. It is about 400^[7] million years old with a high projected rotational velocity of 243 km/s.^[3] This rate of spin is giving the star an oblate shape with a pronounced equatorial bulge that is an estimated 28% wider than the polar radius.^[10]

33 Cyg has 2.33^[3] times the mass of the Sun and 2.76^[6] times the Sun's radius. The star is radiating 44 times the Sun's luminosity from its photosphere at an effective temperature of 8,395 K.^[3] It displays an infrared excess that suggests an orbiting debris disk with a temperature of 500 K at a mean distance of 1.80 AU from the host star.^[6]

References

^ ^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.
^ ^a ^b ^c ^d 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.
^ ^a ^b ^c ^d ^e Zorec, J.; et al. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy and Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
^ ^a ^b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
^ ^a ^b Becker, Juliette C.; et al. (April 2015), "Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra", The Astrophysical Journal Supplement Series, 217 (2): 13, arXiv:1503.03874, Bibcode:2015ApJS..217...29B, doi:10.1088/0067-0049/217/2/29, S2CID 33968873, 29.
^ ^a ^b ^c Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, S2CID 118438871, 15.
^ ^a ^b ^c De Rosa, R. J.; et al. (2014), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932, S2CID 88503488.
^ "33 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-14.
^ Eggen, Olin J. (December 1995), "Reality Tests of Superclusters in the Young Disk Population", Astronomical Journal, 110: 2862, Bibcode:1995AJ....110.2862E, doi:10.1086/117734.
^ 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, S2CID 119273474.