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Tau2 Lupi 
Summary
Tau2 Lupi, Latinized from τ2 Lup, is a binary star[3] system in the constellation Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.34.[2] Based upon an annual parallax shift of 10.22[1] mas as seen from Earth, it is located around 319 light years from the Sun. The two components orbit each other with a period of 26.2 years and a high eccentricity of 0.94.[6] The brighter component is a magnitude 4.93 subgiant star with a stellar classification of F4 IV. Its companion is an A-type star with visual magnitude 5.55 and class A7:.[3]
| 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 | |
| Database references | |
| SIMBAD | data |
References edit
- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ a b c d Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ 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:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ a b Heintz, W. D. (August 1986), "Orbits of 20 visual binaries", Astronomy and Astrophysics Supplement Series, 65 (2): 411–417, Bibcode:1986A&AS...65..411H.
- ^ 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:1970crvs.book.....U.
- ^ "tau02 Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-10.