Gamma Lupi

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Gamma Lupi
Diagram showing star positions and boundaries of the Lupus constellation and its surroundings
Cercle rouge 100%.svg

Location of γ Lupi (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lupus
Right ascension 15h 35m 08.44835s[1]
Declination –41° 10′ 00.3247″[1]
Apparent magnitude (V) 2.77[2]
Spectral type B2 IV[3]
U−B color index –0.82[4]
B−V color index –0.20[4]
Radial velocity (Rv) +2.3[5] km/s
Proper motion (μ) RA: −15.62[1] mas/yr
Dec.: −25.43[1] mas/yr
Parallax (π) 7.75 ± 0.50[1] mas
Distance 420 ± 30 ly
(129 ± 8 pc)
Absolute magnitude (MV) –2.4[2]
Period (P) 190.0 yr
Semi-major axis (a) 0.655"
Eccentricity (e) 0.51
Inclination (i) 95.0°
Longitude of the node (Ω) 94.6°
Periastron epoch (T) 1885.0
Argument of periastron (ω)
γ Lup A
Mass 9.5 ± 0.2[3] M
Luminosity 5,000[2] L
Surface gravity (log g) 3.96[2] cgs
Temperature 20,900[2] K
Rotational velocity (v sin i) 270[7] km/s
Age 18.6 ± 2.4[3] Myr
Other designations
γ Lup, CD −40° 9760, HD 138690, HIP 76297, HR 5776, SAO 225938.[8]
Database references

Gamma Lupi (γ Lupi, γ Lup) is a 3rd-magnitude, B-type blue giant star in the constellation of Lupus. It is also known in ancient Chinese astronomy as 騎官一 or "the 1st (star) of the Cavalry Officer". With a telescope, Gamma Lupi can be resolved into a binary star system in close orbit. This is known as the Gamma Lupi AB system, often abbreviated as γ Lupi AB or γ Lup AB. Gamma Lupi A is itself a spectroscopic binary with a period of 2.8081[9] days.

This star is a proper motion member of the Upper-Centaurus Lupus sub-group in the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[2]

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d e f de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1-2): 44–61, Bibcode:1989A&A...216...44D 
  3. ^ a b c Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883Freely accessible, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  4. ^ a b Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J 
  5. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E 
  6. ^ Hartkopf, W. I.; Mason, B. D.; Worley, C. E., Sixth Catalog of Orbits of Visual Binary Stars, retrieved 2010-11-10 
  7. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B 
  8. ^ "HD 138690", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2007-01-18 
  9. ^ Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573Freely accessible, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213