KY Cygni

From Wikipedia, the free encyclopedia
Jump to: navigation, search
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) 10.77[1]
Spectral type M3m...[1]
B−V color index 2.8[1]
Variable type LC[2]
Mass 25[3] M
Radius 1,420[4] R
Luminosity (bolometric) 270,000–1,100,000[4] L
Surface gravity (log g) −1.0 to −0.5[4] cgs
Temperature 3,500[4] K
Distance ~5,000[5][6] ly
(~1,600[5][6] pc)
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[2]) 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]


  1. ^ a b c d e V* KY Cyg -- Pulsating variable Star, database entry, SIMBAD. Accessed on line November 12, 2010.
  2. ^ a b 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.
  3. ^ List of Largest Stars Gets 3 New Chart Toppers, Robert Roy Britt,, 10 January 2005. Accessed on line November 12, 2010.
  4. ^ a b c d Table 4, Levesque et al. 2005, using Mbol = −10.36/−8.84 for KY Cygni (see the table) and 4.74 for the Sun (p. 982.)
  5. ^ a b KY Cygni is in the Cyg OB1 association, which has an adopted estimated distance modulus of 11.0. See Tables 1 and 2, Levesque et al. 2005.
  6. ^ a b "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought", Emily M. Levesque, Philip Massey, K. A. G. Olsen, Bertrand Plez, Eric Josselin, Andre Maeder, and Georges Meynet, The Astrophysical Journal 628, #2 (August 2005), pp. 973-985, doi:10.1086/430901, Bibcode2005ApJ...628..973L.

External links[edit]