Astronomy:Epsilon Librae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h 24m 11.89101s[1] |
| Declination | −10° 19′ 20.1740″[1] |
| Apparent magnitude (V) | 4.922[2] |
| Characteristics | |
| Spectral type | F3 V[3] or F5 IV[4] |
| U−B color index | +0.080[2] |
| B−V color index | +0.451[2] |
| Astrometry | |
| Proper motion (μ) | RA: −66.52[1] mas/yr Dec.: −154.24[1] mas/yr |
| Parallax (π) | 32.02 ± 0.72[1] mas |
| Distance | 102 ± 2 ly (31.2 ± 0.7 pc) |
| Absolute magnitude (MV) | 2.37[5] |
| Orbit[6] | |
| Period (P) | 226.9437±0.0025 d |
| Semi-major axis (a) | 0.85192±0.00359 au |
| Eccentricity (e) | 0.6649±0.0014 |
| Inclination (i) | 52.6±9.4[7]° |
| Periastron epoch (T) | 2453593.022 ± 0.041 HJD[8] |
| Argument of periastron (ω) (secondary) | 339.84±0.15° |
| Details | |
| ε Lib A | |
| Mass | 1.17±0.02[6] M☉ |
| Radius | 1.5[9] R☉ |
| Luminosity | 9.3[10] L☉ |
| Surface gravity (log g) | 4.13[10] cgs |
| Temperature | 6,552±80[6] K |
| Metallicity [Fe/H] | +0.09[10] dex |
| Rotational velocity (v sin i) | 10[5] km/s |
| Age | 1.5[10] Gyr |
| ε Lib B | |
| Mass | 0.410±0.004[6] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Librae (ε Lib) is the Bayer designation for a binary star system in the zodiac constellation Libra. With an apparent visual magnitude of 4.922,[2] it is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 32.02 mas,[1] it is located about 102 light years away from the Sun.
This is a single-lined spectroscopic binary star system. The pair orbit each other with a period of 226.9 days and an eccentricity of 0.66.[6] The semimajor axis of their orbit is estimated to be 0.85 AU, or 85% of the distance from the Earth to the Sun. The primary, component A, has been catalogued with stellar classifications of F3 V[3] and F5 IV,[4] suggesting that it is an F-type star that either belongs to the main sequence or has evolved into a subgiant as the hydrogen at its core nears exhaustion.
The primary has an estimated 1.17[6] times the mass of the Sun and 1.5 times the Sun's radius. It is around 1.5[10] billion years old and is spinning with a projected rotational velocity of 10[5] km/s. The star radiates 9.3[10] times the solar luminosity from its outer atmosphere at an effective temperature of 6,552 K.[6] The secondary, component B, has 41% of the Sun's mass.[6]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Celis, L. (October 1975), "Photoelectric photometry of late-type variable stars", Astronomy and Astrophysics Supplement Series 22: 9–17, Bibcode: 1975A&AS...22....9C.
- ↑ 3.0 3.1 Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey (Ann Arbor, Michigan: Department of Astronomy, University of Michigan) 5, Bibcode: 1999MSS...C05....0H.
- ↑ 4.0 4.1 Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types", Astronomical Journal 80: 637–641, doi:10.1086/111786, Bibcode: 1975AJ.....80..637M.
- ↑ 5.0 5.1 5.2 Takeda, Yoichi et al. (February 2005), "High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards", Publications of the Astronomical Society of Japan 57 (1): 13–25, doi:10.1093/pasj/57.1.13, Bibcode: 2005PASJ...57...13T.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Katoh, Noriyuki et al. (February 2013), "Determination of Orbital Elements of Spectroscopic Binaries Using High-dispersion Spectroscopy", The Astronomical Journal 145 (2): 12, doi:10.1088/0004-6256/145/2/41, 41, Bibcode: 2013AJ....145...41K.
- ↑ Jancart, S. (2005), "Astrometric orbits of SB9 stars", Astronomy and Astrophysics 442 (1): 365–380, doi:10.1051/0004-6361:20053003, Bibcode: 2005A&A...442..365J.
- ↑ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I. et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics 424 (2): 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
- ↑ Pasinetti-Fracassini, L. E. et al. (February 2001), "Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics 367: 521–524, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P.
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 Takeda, Yoichi (April 2007), "Fundamental Parameters and Elemental Abundances of 160 F-G-K Stars Based on OAO Spectrum Database", Publications of the Astronomical Society of Japan 59 (2): 335–356, doi:10.1093/pasj/59.2.335, Bibcode: 2007PASJ...59..335T.
- ↑ "eps Lib -- Spectroscopic binary", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eps+Lib, retrieved 2017-01-30.
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