Upsilon Librae
Binary star in the constellation Libra
Upsilon Librae (υ Lib, υ Librae) is the Bayer designation for a double star [ 9] in the zodiac constellation Libra . With an apparent visual magnitude of 3.628,[ 2] it is visible to the naked eye. The distance to this star, based upon an annual parallax shift of 14.58,[ 1] is around 224 light years . It has a magnitude 10.8 companion at an angular separation of 2.0 arc seconds along a position angle of 151°, as of 2002.[ 10]
The brighter component is an evolved K-type giant star with a stellar classification of K3 III.[ 3] The measured angular diameter , after correction for limb darkening , is 4.27± 0.05 mas .[ 11] At the estimated distance of the star, this yields a physical size of about 31.5 times the radius of the Sun .[ 7] It has 1.67 times the mass of the Sun and radiates 309 times the solar luminosity from its outer atmosphere at an effective temperature of 4,135 K.[ 6] The star is about three billion years old.[ 6]
Upsilon Librae will be the brightest star in the night sky in about 2.3 million years,[ 12] and will peak in brightness with an apparent magnitude of –0.46.[ 12]
References
^ 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 Celis S., L. (October 1975), "Photoelectric photometry of late-type variable stars", Astronomy and Astrophysics Supplement Series , 22 : 9–17, Bibcode :1975A&AS...22....9C .
^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars , vol. 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode :1982mcts.book.....H
^ 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.
^ Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific , 121 (882): 842, arXiv :0907.3346 , Bibcode :2009PASP..121..842R , doi :10.1086/605456 , S2CID 17821279 .
^ a b c Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal , 150 (3): 23, arXiv :1507.01466 , Bibcode :2015AJ....150...88L , doi :10.1088/0004-6256/150/3/88 , S2CID 118505114 , 88.
^ a b Lang, Kenneth R. (2006), Astrophysical formulae , Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser , ISBN 3-540-29692-1 . The radius (R* ) is given by:
2
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R
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68.6
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4.27
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10
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3
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AU
0.0046491
AU
/
R
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≈ ≈ -->
63.0
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R
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{\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(68.6\cdot 4.27\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 63.0\cdot R_{\bigodot }\end{aligned}}}
^ "ups Lib" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2017-01-30 .
^ 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 .
^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal , 122 (6): 3466, Bibcode :2001AJ....122.3466M , doi :10.1086/323920
^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics , 431 (2): 773–777, Bibcode :2005A&A...431..773R , doi :10.1051/0004-6361:20042039 .
^ a b Tomkin, Jocelyn (April 1998). "Once and Future Celestial Kings". Sky and Telescope . 95 (4): 59–63. Bibcode :1998S&T....95d..59T . based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.) PDF [permanent dead link ]