KY Cygni

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KY Cygni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cygnus
Right ascension 20h 25m 58.05s[1]
Declination +38° 21′ 07.6″[1]
Apparent magnitude (V) 13.50[2] (13.5 - 15.5)[3]
Spectral type M3-4I[4]
B−V color index 0.12[2]
Variable type LC[3]
Distance ~5,000 ly
(1,580[5] pc)
Absolute magnitude (MV) -8.18[4]
Radius 1,420 (2,850?)[4] R
Luminosity (bolometric) 270,000 (1,100,000?)[4] L
Surface gravity (log g) −1.0 (−0.5?)[4] cgs
Temperature 3,500[4] K
Other designations
KY Cyg, AN 339.1929, IRAS 20241+3811, IRC +40415, LEE 220, RAFGL 2575.
Database references

KY Cygni is a red supergiant (spectral class M3.5Ia[3]) located in the constellation Cygnus. It is one of the largest stars known, with an estimated radius of 1,420 and is also one of the most luminous, with about 300,000 or more times the Sun's luminosity. It is approximately 5,000 light-years away.

See also[edit]

Diagram of KY Cygni.


  1. ^ a b Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally published in: University of Massachusetts and Infrared Processing and Analysis Center 2246: 0. Bibcode:2003yCat.2246....0C. 
  2. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237: 0. Bibcode:2002yCat.2237....0D. 
  3. ^ a b c KY Cyg, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 12, 2010.
  4. ^ a b c d e f Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal 628 (2): 973. arXiv:astro-ph/0504337. Bibcode:2005ApJ...628..973L. doi:10.1086/430901. .
  5. ^ Mauron, N.; Josselin, E. (2011). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics 526: A156. arXiv:1010.5369. Bibcode:2011A&A...526A.156M. doi:10.1051/0004-6361/201013993. 

External links[edit]