KW Sagittarii

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KW Sagittarii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 17h 52m 00.7257s
Declination −28° 01′ 20.562″
Apparent magnitude (V) 8.983 (v)

8.5 to 11 (AAVSO)
11.0 to 13.2 (p)[1]

Spectral type M1.5Iab:
Apparent magnitude (K) 1.27
U−B color index 3.21[2]
B−V color index 2.47[2]
V−R color index 2.58[2]
J−K color index 1.56[2]
Variable type SRC[1]
Radius 1,009[2]-1,460[3] R
Luminosity (bolometric) 176,000[2]-360,000[3] L
Surface gravity (log g) 0.0[2]-−0.5[3] cgs
Temperature 3,700[2][3] K
Proper motion (μ) RA: −1.11 mas/yr
Dec.: −1.76 mas/yr
Distance 7,800[2] ly
(2,400[2] pc)
Other designations
KW Sgr, CD−27 12032, HD 316496, HIP 87433.
Database references

KW Sagittarii is a red supergiant, located approximately 2,400 parsecs away from our Sun in the direction of the constellation Sagittarius. The distance is based on the assumption of membership on the Sagittarius OB5 association.[4]

It is over a thousand times the sun's radius, making it one of the largest known stars. Estimates of its bolometric luminosity vary from less than 200,000[2] to over 350,000[3] times the Sun's.

AAVSO light curve of SRC variable star KW Sgr from 1 Jan 1990 to 24 Nov 2010. Up is brighter and down is fainter. Day numbers are Julian day.

See also[edit]


  1. ^ a b KW Sgr, 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 10, 2010. (Quick look: KW+Sgr)
  2. ^ a b c d e f g h i j k Arroyo-Torres, B.; Wittkowski, M.; Marcaide, J. M.; Hauschildt, P. H. (2013). "The atmospheric structure and fundamental parameters of the red supergiants AH Scorpii, UY Scuti, and KW Sagittarii". Astronomy & Astrophysics 554: A76. doi:10.1051/0004-6361/201220920. 
  3. ^ a b c d e Levesque, E. M.; Massey, P.; Olsen, K. A. G.; Plez, B.; Meynet, G.; Maeder, A. (2006). "The Effective Temperatures and Physical Properties of Magellanic Cloud Red Supergiants: The Effects of Metallicity". The Astrophysical Journal 645 (2): 1102. arXiv:astro-ph/0603596. Bibcode:2006ApJ...645.1102L. doi:10.1086/504417. 
  4. ^ Bibcode2009yCat..74000518M

External links[edit]

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