  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h 37m 01.45020s[1] |
| Declination | −28° 08′ 06.2926″[1] |
| Apparent magnitude (V) | 3.628[2] |
| Characteristics | |
| Spectral type | K3 III[3] |
| U−B color index | +1.586[2] |
| B−V color index | +1.374[2] |
| Astrometry | |
| Radial velocity (Rv) | −24.9±0.7[4] km/s |
| Proper motion (μ) | RA: −12.82[1] mas/yr Dec.: −4.15[1] mas/yr |
| Parallax (π) | 14.58±0.19 mas[1] |
| Distance | 224 ± 3 ly (68.6 ± 0.9 pc) |
| Absolute magnitude (MV) | −0.28[5] |
| Details[6] | |
| Mass | 1.67 M☉ |
| Radius | 31.5[7] R☉ |
| Luminosity | 309 L☉ |
| Surface gravity (log g) | 1.58 cgs |
| Temperature | 4,135±20 K |
| Metallicity [Fe/H] | −0.02 dex |
| Age | 3.14 Gyr |
| Other designations | |
| υ Lib, 39 Lib, CD−27°10464, FK5 579, HD 139063, HIP 76470, HR 5794, SAO 183619[8] | |
| Database references | |
| SIMBAD | data |
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, or more than 40 times its present-day brightness.[12]
This star was originally designated by Bayer as Omicron Scorpii, but it was reassigned to Libra as Upsilon Librae.[13]: 196, 278 The star now known as Omicron Scorpii was a reinterpretation of o (Latin letter o) Scorpii, a designation given by Lacaille.
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:
- ^ "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[dead link]
- ^ Wagman, Morton (2003). Lost Stars. McDonald & Woodward. ISBN 0939923785.
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