# Gamma Lupi

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Triple star system in the constellation Lupus

Gamma Lupi 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] Characteristics Spectral type B2 IV[3] U−B color index −0.82[4] B−V color index −0.20[4] Astrometry 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 mas[1] Distance 420 ± 30 ly (129 ± 8 pc) Absolute magnitude (MV) −2.4[2] Orbit[6] Primary Aa Name Ab Period (P) 2.85 days Semi-major axis (a) 16.0–19.3 R☉ Eccentricity (e) 0 Semi-amplitude (K1) (primary) 26.7±1.0 km/s Orbit[6] Primary A Name B Period (P) 167.3+21.5 −7.2 yr Semi-major axis (a) 0.970″+0.343″ −0.240″" (125 AU) Eccentricity (e) 0.826+0.082 −0.181 Inclination (i) 93.04+1.45 −0.89° Longitude of the node (Ω) 91.20+0.52 −0.35° Periastron epoch (T) 1885.7+2.9 −4.0 Argument of periastron (ω) (secondary) 286.9+12.0 −5.9° Details[6] γ Lup Aa Mass 6–10 M☉ Radius 3.92–5.39 R☉ Luminosity 2,570–4,700 L☉ Surface gravity (log g) 3.867–4.130 cgs Temperature 20,900[2] K Rotational velocity (v sin i) 270[7] km/s Age 16.7+5.0 −6.6 Myr γ Lup Ab Mass 0.72–1.93 M☉ Radius 2.00–3.47 R☉ Luminosity 2.39–10.7 L☉ Surface gravity (log g) 3.515–3.803 cgs Temperature 4,140–7,210 K Other designations γ Lup, CD−40°9760, HD 138690, HIP 76297, HR 5776, SAO 225938[8] Database references SIMBAD data

**Gamma Lupi**, [Latinized](/source/Romanization_of_Greek) from γ Lupi, is a triple [star system](/source/Star_system) in the [constellation](/source/Constellation) of [Lupus](/source/Lupus_(constellation)). It is easily visible to the [naked eye](/source/Naked_eye), having an [apparent magnitude](/source/Apparent_magnitude) of 2.77. It is also known in ancient [Chinese](/source/Chinese_language) 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.

A [light curve](/source/Light_curve) for Gamma Lupi, plotted from *[TESS](/source/Transiting_Exoplanet_Survey_Satellite)* data[9]

The system has a hierarchical architecture. The primary, Gamma Lupi A is itself a [spectroscopic binary](/source/Spectroscopic_binary) with an orbital period of 2.849769 days.[6] Although the system does not show eclipses, the hotter star of the pair heats the side of the cooler star that faces it, and as they orbit each other the combined starlight varies in brightness by about 0.02 magnitudes, as seen from the Earth.[10] The outer component, Gamma Lupi B, is widely-separated (125 [astronomical units](/source/Astronomical_unit)) and has an orbital period of 170 years.[6]

This star is a [proper motion](/source/Proper_motion) member of the Upper Centaurus–Lupus sub-group in the [Scorpius–Centaurus](/source/Scorpius%E2%80%93Centaurus_association) [OB association](/source/Stellar_association), the nearest such co-moving association of massive stars to the Sun.[2]

## See also

- [Traditional Chinese star names#Lupus](/source/Traditional_Chinese_star_names#Lupus)

## References

1. ^ [***a***](#cite_ref-aaa474_2_653_1-0) [***b***](#cite_ref-aaa474_2_653_1-1) [***c***](#cite_ref-aaa474_2_653_1-2) [***d***](#cite_ref-aaa474_2_653_1-3) [***e***](#cite_ref-aaa474_2_653_1-4) van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*, **474** (2): 653–664, [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357), [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600)

1. ^ [***a***](#cite_ref-aaa216_1_44_2-0) [***b***](#cite_ref-aaa216_1_44_2-1) [***c***](#cite_ref-aaa216_1_44_2-2) [***d***](#cite_ref-aaa216_1_44_2-3) 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](/source/Bibcode_(identifier)):[1989A&A...216...44D](https://ui.adsabs.harvard.edu/abs/1989A&A...216...44D)

1. **[^](#cite_ref-mnras410_1_190_3-0)** 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](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **410** (1): 190–200, [arXiv](/source/ArXiv_(identifier)):[1007.4883](https://arxiv.org/abs/1007.4883), [Bibcode](/source/Bibcode_(identifier)):[2011MNRAS.410..190T](https://ui.adsabs.harvard.edu/abs/2011MNRAS.410..190T), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2010.17434.x](https://doi.org/10.1111%2Fj.1365-2966.2010.17434.x), [S2CID](/source/S2CID_(identifier)) [118629873](https://api.semanticscholar.org/CorpusID:118629873)

1. ^ [***a***](#cite_ref-clpl4_99_4-0) [***b***](#cite_ref-clpl4_99_4-1) Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", *Communications of the Lunar and Planetary Laboratory*, **4** (99): 99, [Bibcode](/source/Bibcode_(identifier)):[1966CoLPL...4...99J](https://ui.adsabs.harvard.edu/abs/1966CoLPL...4...99J)

1. **[^](#cite_ref-rgcrv_5-0)** Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", *Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30*, vol. 30, University of Toronto: [International Astronomical Union](/source/International_Astronomical_Union), p. 57, [Bibcode](/source/Bibcode_(identifier)):[1967IAUS...30...57E](https://ui.adsabs.harvard.edu/abs/1967IAUS...30...57E)

1. ^ [***a***](#cite_ref-Jerzykiewicz_6-0) [***b***](#cite_ref-Jerzykiewicz_6-1) [***c***](#cite_ref-Jerzykiewicz_6-2) [***d***](#cite_ref-Jerzykiewicz_6-3) [***e***](#cite_ref-Jerzykiewicz_6-4) Jerzykiewicz, M.; Pigulski, A.; Michalska, G.; Moździerski, D.; Ratajczak, M.; Handler, G.; Moffat, A. F. J.; Pablo, H.; Popowicz, A.; Wade, G. A.; Zwintz, K. (June 2021). ["BRITE observations of ν Centauri and γ Lupi, the first non-eclipsing members of the new class of nascent binaries"](https://doi.org/10.1093%2Fmnras%2Fstab846). *Monthly Notices of the Royal Astronomical Society*. **503** (4): 5554–5568. [arXiv](/source/ArXiv_(identifier)):[2104.11770](https://arxiv.org/abs/2104.11770). [Bibcode](/source/Bibcode_(identifier)):[2021MNRAS.503.5554J](https://ui.adsabs.harvard.edu/abs/2021MNRAS.503.5554J). [doi](/source/Doi_(identifier)):[10.1093/mnras/stab846](https://doi.org/10.1093%2Fmnras%2Fstab846).

1. **[^](#cite_ref-coapa239_1_7-0)** Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", *Contributi Osservatorio Astronomico di Padova in Asiago*, **239** (1): 1, [Bibcode](/source/Bibcode_(identifier)):[1970CoAsi.239....1B](https://ui.adsabs.harvard.edu/abs/1970CoAsi.239....1B)

1. **[^](#cite_ref-SIMBAD_8-0)** ["* gam Lup"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+gam+Lup). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2007-01-18.

1. **[^](#cite_ref-MAST_9-0)** ["MAST: Barbara A. Mikulski Archive for Space Telescopes"](https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html). Space Telescope Science Institute. Retrieved 8 December 2021.

1. **[^](#cite_ref-IVSI_10-0)** ["gam Lup"](https://www.aavso.org/vsx/index.php?view=detail.top&oid=17893). *The International Variable Star Index*. AAVSO. Retrieved 16 December 2022.

v t e Constellation of Lupus List of stars in Lupus Lupus in Chinese astronomy Stars Bayer α (Uridim) β γ δ ε ζ η θ ι κ λ μ ν1 ν2 ξ ο π ρ σ τ1 τ2 υ φ1 φ2 χ ψ1 ψ2 ω Flamsteed 1 (i) 2 (f) Variable RU EX GG GQ HR II IL IM KT (d) V407 V462 HR 5362 5364 5401 5651 (e) 5724 (k) 5825 (g) 5943 5967 HD 134004 135344 136164 141943 142527 143811 Other Gliese 588 HIP 70849 Lupus-TR-3 SSSPM J1549−3544 WASP-132 Exoplanets GQ Lupi b HIP 70849 b Lupus-TR-3b WASP-178b Star clusters NGC 5749 NGC 5822 NGC 5824 NGC 5927 NGC 5986 Nebulae IC 4406 NGC 5882 Galaxies IC 4444 NGC 5530 NGC 5643 Astronomical events SN 1006 Category

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Adapted from the Wikipedia article [Gamma Lupi](https://en.wikipedia.org/wiki/Gamma_Lupi) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Gamma_Lupi?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.