# Tau2 Lupi

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Binary star system in the constellation Lupus

For other stars with this Bayer designation, see [τ Lupi](/source/Tau_Lupi).

Tau2 Lupi Location of τ2 Lupi (circled in red) Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) Constellation Lupus Right ascension 14h 26m 10.81378s[1] Declination −45° 22′ 45.4023″[1] Apparent magnitude (V) 4.34[2] (4.93 + 5.55)[3] Characteristics Spectral type F4 IV + A7:[3] U−B color index +0.16[2] B−V color index +0.43[2] Astrometry Radial velocity (Rv) −0.60±1.60[4] km/s Proper motion (μ) RA: +14.62[1] mas/yr Dec.: −7.33[1] mas/yr Parallax (π) 10.22±0.31 mas[1] Distance 319 ± 10 ly (98 ± 3 pc) Absolute magnitude (MV) −0.62[5] Orbit[6] Period (P) 26.2 yr Semi-major axis (a) 0.125″ Eccentricity (e) 0.94 Inclination (i) 56.0° Longitude of the node (Ω) 175.7° Periastron epoch (T) 1969.1 Argument of periastron (ω) (secondary) 191.0° Details Luminosity 150[5] L☉ Rotational velocity (v sin i) 0[7] km/s Other designations τ2 Lup, CD−44°9323, HD 126354, HIP 70576, HR 5396, SAO 224920[8] Database references SIMBAD data

**Tau2 Lupi**, [Latinized](/source/Latinisation_of_names) from **τ2 Lup**, is a [binary star](/source/Binary_star)[3] 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 4.34.[2] Based upon an annual [parallax shift](/source/Stellar_parallax) of 10.22[1] [mas](/source/Milliarcsecond) as seen from Earth, it is located around 319 [light years](/source/Light_year) from the [Sun](/source/Sun). The two components orbit each other with a [period](/source/Orbital_period) of 26.2 years and a high [eccentricity](/source/Orbital_eccentricity) of 0.94.[6] The brighter component is a magnitude 4.93 [subgiant star](/source/Subgiant_star) with a [stellar classification](/source/Stellar_classification) of F4 IV. Its companion is an [A-type star](/source/A-type_star) with visual magnitude 5.55 and class A7:.[3]

## References

1. ^ [***a***](#cite_ref-vanLeeuwen2007_1-0) [***b***](#cite_ref-vanLeeuwen2007_1-1) [***c***](#cite_ref-vanLeeuwen2007_1-2) [***d***](#cite_ref-vanLeeuwen2007_1-3) [***e***](#cite_ref-vanLeeuwen2007_1-4) [***f***](#cite_ref-vanLeeuwen2007_1-5) 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-Mermilliod1986_2-0) [***b***](#cite_ref-Mermilliod1986_2-1) [***c***](#cite_ref-Mermilliod1986_2-2) [***d***](#cite_ref-Mermilliod1986_2-3) Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", *Catalogue of Eggen's UBV Data*, [SIMBAD](/source/SIMBAD), [Bibcode](/source/Bibcode_(identifier)):[1986EgUBV........0M](https://ui.adsabs.harvard.edu/abs/1986EgUBV........0M).

1. ^ [***a***](#cite_ref-Eggleton2008_3-0) [***b***](#cite_ref-Eggleton2008_3-1) [***c***](#cite_ref-Eggleton2008_3-2) [***d***](#cite_ref-Eggleton2008_3-3) Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **389** (2): 869–879, [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. **[^](#cite_ref-deBruijne2012_4-0)** 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-Anderson2012_5-0) [***b***](#cite_ref-Anderson2012_5-1) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *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), [S2CID](/source/S2CID_(identifier)) [119257644](https://api.semanticscholar.org/CorpusID:119257644).

1. ^ [***a***](#cite_ref-Heintz1986_6-0) [***b***](#cite_ref-Heintz1986_6-1) Heintz, W. D. (August 1986), "Orbits of 20 visual binaries", *Astronomy and Astrophysics Supplement Series*, **65** (2): 411–417, [Bibcode](/source/Bibcode_(identifier)):[1986A&AS...65..411H](https://ui.adsabs.harvard.edu/abs/1986A&AS...65..411H).

1. **[^](#cite_ref-Uesugi1970_7-0)** Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", *Contributions from the Institute of Astrophysics and Kwasan Observatory*, University of Kyoto, [Bibcode](/source/Bibcode_(identifier)):[1970crvs.book.....U](https://ui.adsabs.harvard.edu/abs/1970crvs.book.....U).

1. **[^](#cite_ref-SIMBAD_8-0)** ["tau02 Lup"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tau02+Lup). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2017-03-10.

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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