KW Sagittarii

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KW Sagittarii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 17h 52m 00.72665s[1]
Declination −28° 01′ 20.5622″[1]
Apparent magnitude (V) 11.0[2]

8.5 to 11 (AAVSO)
11.0 to 13.2 (p)[3]

Characteristics
Spectral type M1.5Iab[4]
Apparent magnitude (K) 1.43[2]
U−B color index 3.21[4]
B−V color index 2.47[4]
V−R color index 2.58[4]
J−K color index 1.56[4]
Variable type SRC[3]
Astrometry
Radial velocity (Rv) −7.40[5] km/s
Proper motion (μ) RA: 0.39[1] mas/yr
Dec.: −1.62[1] mas/yr
Parallax (π) −2.43 ± 0.94[1] mas
Distance 7,800[4] ly
(2,400 pc)
Details
Radius 1,009[4](-1,460[6]R
Luminosity (bolometric) 176,000[4]-360,000[6] L
Surface gravity (log g) 0.0[4]-−0.5[6] cgs
Temperature 3,700[4][6] K
Other designations
KW Sgr, CD−27°12032, HD 316496, HIP 87433, AAVSO 1745-28
Database references
SIMBAD data

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.[7]

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 to over 350,000 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]

References[edit]

  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  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. Bibcode:2002yCat.2237....0D. 
  3. ^ 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)
  4. ^ a b c d e f g h i j 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. arXiv:1305.6179. Bibcode:2013A&A...554A..76A. doi:10.1051/0004-6361/201220920. 
  5. ^ Barbier-Brossat, M.; Petit, M.; Figon, P. (1994). "Third bibliographic catalogue of stellar radial velocities (Text in French)". Astronomy and Astrophysics Supplement Series 108. Bibcode:1994A&AS..108..603B. 
  6. ^ a b c d 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. 
  7. ^ Melnik, A. M.; Dambis, A. K. (2009). "VizieR Online Data Catalog: Velocity and proper motion of OB associations (Melnik+, 2009)". VizieR On-line Data Catalog: J/MNRAS/400/518. Originally published in: 2009MNRAS.400..518M 740. Bibcode:2009yCat..74000518M. 

External links[edit]

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