V4381 Sagittarii

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V4381 Sagittarii
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 08m 38.58558s[1]
Declination −21° 26′ 58.4136″[1]
Apparent magnitude (V) 6.538[2] (6.57p - 6.62p[3])
Evolutionary stage Supergiant[2]
Spectral type A2/A3Iab[2]
U−B color index +0.279[2]
B−V color index −+0.856[2]
Variable type α Cyg[3]
Radial velocity (Rv) −16[4] km/s
Proper motion (μ) RA: −1.65[1] mas/yr
Dec.: −1.05[1] mas/yr
Parallax (π) 2.25 ± 0.55[1] mas
Distance approx. 1,400 ly
(approx. 400 pc)
Absolute magnitude (MV) −6.6[5]
Mass 7.00[6] M
Luminosity 39,000 L
Surface gravity (log g) 1.50 cgs
Temperature 9,000 K
Rotational velocity (v sin i) 18 km/s
Other designations
V4381 Sagittarii, HD 165784, HIP 48766, BD−21°4866, 2MASS J18083858-2126584
Database references

V4381 Sagittarii is a variable star in the constellation Sagittarius. A white supergiant of spectral type A2/A3Iab, it is an Alpha Cygni variable that varies between apparent magnitudes 6.57 and 6.62.


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e f Firnstein, M.; Przybilla, N. (2012). "Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters". Astronomy & Astrophysics 543: A80. arXiv:1207.0308. Bibcode:2012A&A...543A..80F. doi:10.1051/0004-6361/201219034. 
  3. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S 1. Bibcode:2009yCat....102025S. 
  4. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  5. ^ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559. 
  6. ^ Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten 331 (4): 349. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355.