# KT Lupi

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Visual binary star system in the constellation of Lupus

This article is about d Lupi; not to be confused with [δ Lupi](/source/Delta_Lupi).

KT Lupi Location of KT Lupi (circled in red) Observation data Epoch J2000 Equinox J2000 Constellation Lupus[1] Right ascension 15h 35m 53.24806s[2] Declination −44° 57′ 30.1982″[2] Apparent magnitude (V) 4.55[1] (4.66 + 6.62)[3] Characteristics Spectral type B3 V + B6 V[4] B−V color index −0.175±0.003[1] Variable type Be[5] Astrometry Radial velocity (Rv) +6.5±2.8[6] km/s Proper motion (μ) RA: −20.53[2] mas/yr Dec.: −21.23[2] mas/yr Parallax (π) 7.62±0.43 mas[2] Distance 430 ± 20 ly (131 ± 7 pc) Absolute magnitude (MV) −1.03[1] Details KT Lup A Mass 5.9±0.1[7] M☉ Radius 3.00±0.06[8] R☉ Luminosity 794+791 −396[9] L☉ Surface gravity (log g) 3.50±0.04[8] cgs Temperature 18,400±184[8] K Rotational velocity (v sin i) 30±0.6[8] km/s Age 21.0±10.6[7] Myr KT Lup B Mass 2.79[10] M☉ Other designations d Lup, KT Lup, CD−44°10239, HD 138769, HIP 76371, HR 5781, SAO 225950, WDS J15359-4457AB[11] Database references SIMBAD data

**KT Lupi** is a visual [binary star](/source/Binary_star)[4] system in the [constellation](/source/Constellation) [Lupus](/source/Lupus_(constellation)). It is visible to the naked eye with a combined [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.55.[1] As of 1983, the pair had an [angular separation](/source/Angular_separation) of 2.19[″](/source/Second_of_arc)±0.03[″](/source/Second_of_arc).[9] Based upon an annual [parallax shift](/source/Stellar_parallax) of 7.6 [mas](/source/Milliarcsecond)[2] as seen from Earth's orbit, it is located 430 [light-years](/source/Light-year) from the [Sun](/source/Sun). The system is moving further from the Earth with a heliocentric [radial velocity](/source/Radial_velocity) of +6.5 km/s.[6] It is a member of the Upper Centaurus-Lupus sub-group of the [Scorpius–Centaurus association](/source/Scorpius%E2%80%93Centaurus_association).[4]

A [light curve](/source/Light_curve) for KT Lupi, plotted from *[Hipparcos](/source/Hipparcos)* data [12]

The primary, component A, is a [variable](/source/Variable_star) [Be star](/source/Be_star),[5] with the variation being modulated by rotation.[13] It is visual magnitude 4.66[3] with a [stellar classification](/source/Stellar_classification) of B3 V,[4] matching a [B-type main-sequence star](/source/B-type_main-sequence_star). Hiltner et al. (1969) gave a class of B3 IVp,[14] which is still used in some studies.[7][8][9] It is a helium-weak [chemically peculiar star](/source/Chemically_peculiar_star) showing an enhanced [silicon](/source/Silicon) patch near the equator and a silicon-weak region close to the pole.[9] The star is about 21 million years old with nearly six[7] times the [mass of the Sun](/source/Mass_of_the_Sun) and three times the [Sun's radius](/source/Sun's_radius).[8] It is radiating roughly 794[9] times the [Sun's luminosity](/source/Sun's_luminosity) from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 18,400 [K](/source/Kelvin).[8]

The secondary companion, component B, is of magnitude 6.62[3] with a class of B6 V.[4] It has 2.79 times the [Sun's mass](/source/Sun's_mass).[10]

## References

1. ^ [***a***](#cite_ref-Anderson2012_1-0) [***b***](#cite_ref-Anderson2012_1-1) [***c***](#cite_ref-Anderson2012_1-2) [***d***](#cite_ref-Anderson2012_1-3) [***e***](#cite_ref-Anderson2012_1-4) Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". *[Astronomy Letters](/source/Astronomy_Letters)*. **38** (5): 331. [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971). [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A). [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [XHIP record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-ref=VIZ681510a8389ecb&-out.src=V%2F137D%2FXHIP&-nav=cat%3AV%2F137D%26tab%3A{V%2F137D%2FXHIP}%26key%3Asource%3DV%2F137D%2FXHIP%26HTTPPRM%3A&-source=V%2F137D%2FXHIP&-out=HIP&HIP=76371&-out=Comp&-out=Gr&-out=RAJ2000&-out=DEJ2000&-out=Dist&-out=X&-out=Y&-out=Z&-out=SpType&-out=Simbad&-out=Hpmag&-out=Lum&-out=Cst) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-vanLeeuwen2007_2-0) [***b***](#cite_ref-vanLeeuwen2007_2-1) [***c***](#cite_ref-vanLeeuwen2007_2-2) [***d***](#cite_ref-vanLeeuwen2007_2-3) [***e***](#cite_ref-vanLeeuwen2007_2-4) [***f***](#cite_ref-vanLeeuwen2007_2-5) van Leeuwen, F. (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-Eggleton2008_3-0) [***b***](#cite_ref-Eggleton2008_3-1) [***c***](#cite_ref-Eggleton2008_3-2) Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", *Monthly Notices of the Royal Astronomical Society*, **389** (2): 869, [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878), [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x), [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. ^ [***a***](#cite_ref-Chen2012_4-0) [***b***](#cite_ref-Chen2012_4-1) [***c***](#cite_ref-Chen2012_4-2) [***d***](#cite_ref-Chen2012_4-3) [***e***](#cite_ref-Chen2012_4-4) Chen, Christine H.; et al. (September 2012), "A Spitzer MIPS Study of 2.5–2.0 M☉ Stars in Scorpius–Centaurus", *The Astrophysical Journal*, **756** (2): 24, [arXiv](/source/ArXiv_(identifier)):[1207.3415](https://arxiv.org/abs/1207.3415), [Bibcode](/source/Bibcode_(identifier)):[2012ApJ...756..133C](https://ui.adsabs.harvard.edu/abs/2012ApJ...756..133C), [doi](/source/Doi_(identifier)):[10.1088/0004-637X/756/2/133](https://doi.org/10.1088%2F0004-637X%2F756%2F2%2F133), [S2CID](/source/S2CID_(identifier)) [119278056](https://api.semanticscholar.org/CorpusID:119278056), 133.

1. ^ [***a***](#cite_ref-gcvs_5-0) [***b***](#cite_ref-gcvs_5-1) Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", *Astronomy Reports*, **61** (1): 80, [Bibcode](/source/Bibcode_(identifier)):[2017ARep...61...80S](https://ui.adsabs.harvard.edu/abs/2017ARep...61...80S), [doi](/source/Doi_(identifier)):[10.1134/S1063772917010085](https://doi.org/10.1134%2FS1063772917010085), [S2CID](/source/S2CID_(identifier)) [125853869](https://api.semanticscholar.org/CorpusID:125853869).

1. ^ [***a***](#cite_ref-deBruijne2012_6-0) [***b***](#cite_ref-deBruijne2012_6-1) de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", *Astronomy & Astrophysics*, **546**: 14, [arXiv](/source/ArXiv_(identifier)):[1208.3048](https://arxiv.org/abs/1208.3048), [Bibcode](/source/Bibcode_(identifier)):[2012A&A...546A..61D](https://ui.adsabs.harvard.edu/abs/2012A&A...546A..61D), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201219219](https://doi.org/10.1051%2F0004-6361%2F201219219), [S2CID](/source/S2CID_(identifier)) [59451347](https://api.semanticscholar.org/CorpusID:59451347), A61.

1. ^ [***a***](#cite_ref-Tetzlaff2011_7-0) [***b***](#cite_ref-Tetzlaff2011_7-1) [***c***](#cite_ref-Tetzlaff2011_7-2) [***d***](#cite_ref-Tetzlaff2011_7-3) Tetzlaff, N.; et al. (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](/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-Arcos2018_8-0) [***b***](#cite_ref-Arcos2018_8-1) [***c***](#cite_ref-Arcos2018_8-2) [***d***](#cite_ref-Arcos2018_8-3) [***e***](#cite_ref-Arcos2018_8-4) [***f***](#cite_ref-Arcos2018_8-5) [***g***](#cite_ref-Arcos2018_8-6) Arcos, C.; et al. (March 2018), "Stellar parameters and H α line profile variability of Be stars in the BeSOS survey", *Monthly Notices of the Royal Astronomical Society*, **474** (4): 5287–5299, [arXiv](/source/ArXiv_(identifier)):[1711.08675](https://arxiv.org/abs/1711.08675), [Bibcode](/source/Bibcode_(identifier)):[2018MNRAS.474.5287A](https://ui.adsabs.harvard.edu/abs/2018MNRAS.474.5287A), [doi](/source/Doi_(identifier)):[10.1093/mnras/stx3075](https://doi.org/10.1093%2Fmnras%2Fstx3075), [S2CID](/source/S2CID_(identifier)) [74872624](https://api.semanticscholar.org/CorpusID:74872624).

1. ^ [***a***](#cite_ref-Briquet2007_9-0) [***b***](#cite_ref-Briquet2007_9-1) [***c***](#cite_ref-Briquet2007_9-2) [***d***](#cite_ref-Briquet2007_9-3) [***e***](#cite_ref-Briquet2007_9-4) Briquet, M.; et al. (January 2007), "Discovery of magnetic fields in three He variable Bp stars with He and Si spots", *Astronomische Nachrichten*, **328** (1): 41–45, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0610537](https://arxiv.org/abs/astro-ph/0610537), [Bibcode](/source/Bibcode_(identifier)):[2007AN....328...41B](https://ui.adsabs.harvard.edu/abs/2007AN....328...41B), [doi](/source/Doi_(identifier)):[10.1002/asna.200610702](https://doi.org/10.1002%2Fasna.200610702), [S2CID](/source/S2CID_(identifier)) [18724568](https://api.semanticscholar.org/CorpusID:18724568).

1. ^ [***a***](#cite_ref-Kouwenhoven2007_10-0) [***b***](#cite_ref-Kouwenhoven2007_10-1) Kouwenhoven, M. B. N.; et al. (October 2007), "The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2", *Astronomy and Astrophysics*, **474** (1): 77–104, [arXiv](/source/ArXiv_(identifier)):[0707.2746](https://arxiv.org/abs/0707.2746), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474...77K](https://ui.adsabs.harvard.edu/abs/2007A&A...474...77K), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20077719](https://doi.org/10.1051%2F0004-6361%3A20077719), [S2CID](/source/S2CID_(identifier)) [15750945](https://api.semanticscholar.org/CorpusID:15750945).

1. **[^](#cite_ref-SIMBAD_11-0)** ["KT Lup"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=KT+Lup). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 3 September 2018.

1. **[^](#cite_ref-HipDataAccess_12-0)** ["Hipparcos Tools Interactive Data Access"](https://www.cosmos.esa.int/web/hipparcos/interactive-data-access). *Hipparcos*. ESA. Retrieved 8 December 2021.

1. **[^](#cite_ref-Briquet2004_13-0)** Briquet, M.; et al. (January 2004), "He and Si surface inhomogeneities of four Bp variable stars", *Astronomy and Astrophysics*, **413**: 273–283, [Bibcode](/source/Bibcode_(identifier)):[2004A&A...413..273B](https://ui.adsabs.harvard.edu/abs/2004A&A...413..273B), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20031450](https://doi.org/10.1051%2F0004-6361%3A20031450)

1. **[^](#cite_ref-Hiltner1969_14-0)** Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", *Astrophysical Journal*, **157**: 313, [Bibcode](/source/Bibcode_(identifier)):[1969ApJ...157..313H](https://ui.adsabs.harvard.edu/abs/1969ApJ...157..313H), [doi](/source/Doi_(identifier)):[10.1086/150069](https://doi.org/10.1086%2F150069)

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 [KT Lupi](https://en.wikipedia.org/wiki/KT_Lupi) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/KT_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.