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.
| 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 |
| Distance | 219 ± 6 ly (67 ± 2 pc) |
| Absolute magnitude (MV) | 0.80[2] |
| Details[3] | |
| Mass | 1.10±0.22 M☉ |
| Radius | 10.32±0.60 R☉ |
| Luminosity | 59+15 −12 L☉ |
| Surface gravity (log g) | 2.42±0.09 cgs |
| Temperature | 4,749±54 K |
| Metallicity [Fe/H] | −0.32±0.09 dex |
| Rotational velocity (v sin i) | 3.74±0.48 km/s |
| Age | 5.05±2.67 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
- 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.
- 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.
- 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, A50.
- "11 Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-01.
- 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.
- Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
- 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.
- 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, 20.