49 Librae
49 Librae is the Flamsteed designation for a binary star[8] system in the Zodiac constellation of Libra. It has an apparent visual magnitude of 5.47,[2] making it faintly visible to the naked eye from dark suburban skies as a dim, yellow-white hued star. The system is located 95 light years away from the Sun, based on parallax,[1] but is drifting closer with a radial velocity of −20 km/s.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Libra |
| Right ascension | 16h 00m 19.61087s[1] |
| Declination | –16° 32′ 00.5483″[1] |
| Apparent magnitude (V) | 5.47[2] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | F8 V[3] |
| U−B color index | +0.03[2] |
| B−V color index | +0.52[2] |
| Astrometry | |
| Radial velocity (Rv) | −20.1±4.0[4] km/s |
| Proper motion (μ) | RA: –644.387[1] mas/yr Dec.: –360.803[1] mas/yr |
| Parallax (π) | 34.2281 ± 0.1906[1] mas |
| Distance | 95.3 ± 0.5 ly (29.2 ± 0.2 pc) |
| Absolute magnitude (MV) | 2.89[4] |
| Orbit[3] | |
| Period (P) | 1,142.4±1.1 d |
| Semi-major axis (a) | ≥ 59.53±0.244 Gm |
| Eccentricity (e) | 0.110±0.012 |
| Inclination (i) | 143.0±2.0° |
| Longitude of the node (Ω) | 163.5±2.8° |
| Periastron epoch (T) | 57025±22 MJD |
| Argument of periastron (ω) (secondary) | 69.4±7.4° |
| Semi-amplitude (K1) (primary) | 3.847±0.051 km/s |
| Details | |
| 49 Lib A | |
| Mass | 1.4[3] M☉ |
| Radius | 1.86+0.05 −0.04[1] R☉ |
| Luminosity | 4.74±0.03[1] L☉ |
| Surface gravity (log g) | 4.14[5] cgs |
| Temperature | 6,237[4] K |
| Metallicity [Fe/H] | –0.02[4] dex |
| Rotational velocity (v sin i) | 9.6±1.0[3] km/s |
| Age | 12[6] Gyr |
| 49 Lib B | |
| Mass | 0.45[3] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The variable nature of the velocity for 49 Librae was first noted by W. S. Adams in 1924. It is a single-lined spectroscopic binary with an orbital period of 3.128 years and an eccentricity of 0.11.[3] The primary component has a stellar classification of F8 V or F9 V,[3] indicating it is an F-type main-sequence star. It has an estimated 1.4 times the mass of the Sun, while the companion only has 0.4 solar masses.[3] The system is a source for radio and X-ray emissions, which may be coming from the secondary companion.[9]
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Nicolet, B. (October 1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
- Willmarth, Daryl W.; et al. (August 2016), "Spectroscopic Orbits for 15 Late-type Stars" (PDF), The Astronomical Journal, 152 (2): 13, Bibcode:2016AJ....152...46W, doi:10.3847/0004-6256/152/2/46, 46.
- Nordström, B.; et al. (November 2007), "The Geneva-Copenhagen survey of the Solar neighbourhood. II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk", Astronomy & Astrophysics, 475 (2): 519–537, arXiv:0707.1891, Bibcode:2007A&A...475..519H, doi:10.1051/0004-6361:20077221.
- Balachandran, Suchitra (May 1, 1990), "Lithium depletion and rotation in main-sequence stars", Astrophysical Journal, Part 1, 354: 310–332, Bibcode:1990ApJ...354..310B, doi:10.1086/168691.
- Fuhrmann, K.; Chini, R. (January 2, 2017), "Bright Times for an Ancient Star", The Astrophysical Journal, 834 (2): 114, Bibcode:2017ApJ...834..114F, doi:10.3847/1538-4357/834/2/114.
- "49 Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-11-06.
- Abt, Helmut A. (January 2009), "MK Classifications of Spectroscopic Binaries", The Astrophysical Journal Supplement, 180 (1): 117–118, Bibcode:2009ApJS..180..117A, doi:10.1088/0067-0049/180/1/117.
- Lazio, T. Joseph W.; et al. (January 2010), "A Blind Search for Magnetospheric Emissions from Planetary Companions to Nearby Solar-Type Stars", The Astronomical Journal, 139 (1): 96–101, arXiv:0910.3938, Bibcode:2010AJ....139...96L, doi:10.1088/0004-6256/139/1/96.