11 Librae

11 Librae is a single,[5] fifth-magnitude star in the southern zodiac constellation of Libra. It is faintly visible to the naked eye with an apparent visual magnitude is 4.93.[2] The star is moving closer to the Sun with a heliocentric radial velocity of +83.6 km/s.[3] The distance to this star, as estimated from its annual parallax shift of 14.92±0.40 mas,[1] is about 219 light years.

11 Librae
Observation data
Epoch J2000      Equinox J2000
Constellation Libra
Right ascension 14h 51m 01.07273s[1]
Declination −02° 17′ 56.9488″[1]
Apparent magnitude (V) 4.93[2]
Characteristics
Spectral type K0 III-IV[2]
B−V color index 0.988±0.001[2]
Astrometry
Radial velocity (Rv)+83.60±0.06[3] km/s
Proper motion (μ) RA: +89.97[1] mas/yr
Dec.: −124.57[1] mas/yr
Parallax (π)14.92 ± 0.40[1] mas
Distance219 ± 6 ly
(67 ± 2 pc)
Absolute magnitude (MV)0.80[2]
Details[3]
Mass1.10±0.22 M☉
Radius10.32±0.60 R☉
Luminosity59+15
−12 L☉
Surface gravity (log g)2.42±0.09 cgs
Temperature4,749±54 K
Metallicity [Fe/H]−0.32±0.09 dex
Rotational velocity (v sin i)3.74±0.48 km/s
Age5.05±2.67 Myr
Other designations
11 Lib, BD−01° 2991, HD 130952, HIP 72631, HR 5535, SAO 140176[4]
Database references
SIMBADdata

This star has a stellar classification of K0 III/IV,[6] indicating the spectrum displays mixed traits of a giant/subgiant K-type star. Alves (2000) and Afşar et al. (2012) classify it as a red clump star, which means it is an evolved star on the horizontal branch and is generating energy through helium fusion in its core region.[7][8] It is about five billion years old and is spinning with a projected rotational velocity of 4 km/s. The star has 1.1 times the mass of the Sun and has expanded to over 10 times the Sun's radius. It is radiating around 59 times the Sun's radius from its enlarged photosphere at an effective temperature of about 4,749 K.[3]

References
  1. 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.
  2. 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.
  3. Jofré, E.; et al. (February 2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: 46, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.
  4. "11 Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-01.
  5. 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.
  6. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  7. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732−741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.
  8. Afşar, M.; et al. (July 2012), "Chemical Compositions of Thin-disk, High-metallicity Red Horizontal-branch Field Stars", The Astronomical Journal, 144 (1): 20, arXiv:1205.3659, Bibcode:2012AJ....144...20A, doi:10.1088/0004-6256/144/1/20, S2CID 119249237, 20.
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