Alpha Librae
 Location of α Librae (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Libra |
| α1 Lib | |
| Right ascension | 14h 50m 41.18097s |
| Declination | –15° 59′ 50.0482″ |
| Apparent magnitude (V) | +5.153 |
| α2 Lib | |
| Right ascension | 14h 50m 52.71309s |
| Declination | –16° 02′ 30.3955″ |
| Apparent magnitude (V) | +2.741 |
| Characteristics | |
| α1 Lib | |
| Spectral type | F3 V |
| U−B color index | –0.02 |
| B−V color index | +0.39 |
| α2 Lib | |
| Spectral type | kA2hA5mA4 IV-V |
| U−B color index | +0.10 |
| B−V color index | +0.15 |
| Astrometry | |
| α1 Lib | |
| Radial velocity (Rv) | 23.8 km/s |
| Proper motion (μ) |
RA: –136.27 mas/yr Dec.: –59.04 mas/yr |
| Parallax (π) | 43.52 ± 0.43mas |
| Distance | 74.9 ± 0.7 ly (23.0 ± 0.2 pc) |
| Absolute magnitude (MV) | +3.35 |
| α2 Lib | |
| Proper motion (μ) |
RA: –105.68 mas/yr Dec.: –68.40 mas/yr |
| Parallax (π) | 43.03 ± 0.19mas |
| Distance | 75.8 ± 0.3 ly (23.2 ± 0.1 pc) |
| Orbit | |
| Period (P) | 70.34 days |
| Semi-major axis (a) | 0.51 au |
| Eccentricity (e) | 0.41 |
|
Semi-amplitude (K2) (secondary) |
43.1 km/s |
| Details | |
| α1 Lib | |
| Mass | 1.97 + 1.60 M☉ |
| Surface gravity (log g) | 4.25 cgs |
| Temperature | 6,653 K |
| Metallicity [Fe/H] | –0.07 dex |
| Rotational velocity (v sin i) | 5.95 km/s |
| Age |
1.1+0.6 −0.8 Gyr |
| α2 Lib | |
| Mass | 1.4–1.5/0.5–0.6 M☉ |
| Surface gravity (log g) | 3.91 cgs |
| Temperature | 8128 K |
| Other designations | |
|
α Librae, α Lib, alf Lib, Kiffa Australis, Lanx australis, Zubenelgenubi.
|
|
| α1 Lib: 8 Librae, BD–15 3965, FK5 1387, HD 130819, HIP 72603, HR 5530, SAO 158836. | |
| α2 Lib: 9 Librae, BD–15 3966, FK5 548, HD 130841, HIP 72622, HR 5531, SAO 158840. | |
| Database references | |
| SIMBAD | α Lib |
| α1 Lib | |
| α2 Lib | |
Alpha Librae (α Librae, abbreviated Alpha Lib, α Lib), is a double star and despite its 'alpha' designation the second-brightest star in the constellation of Libra. The two components are designated α¹ Librae and α² Librae. The system bore the traditional name of Zubenelgenubi, though the International Astronomical Union now regards that name as only applying to α² Librae.
Alpha² Librae is 0.33 degree from the ecliptic so it can be easily occulted by the Moon and (very rarely) by planets. The next occultation by a planet will be by Mercury on 10 November 2052.
α Librae (Latinised to Alpha Librae) is the system's Bayer designation.
Zubenelgenubi /ˌzuːbənɛldʒəˈnuːbi/, also rendered Zuben Elgenubi, derives from the Arabic ّالزُبَانَى الجَنُوبِي al-zubānā al-janūbiyy "the southern claw", which was coined before Libra was recognized as a constellation distinct from Scorpius. The alternative name Kiffa Australis (Elkhiffa Australis) is a partial Latin translation of the Arabic al-kiffah al-janūbiyy "southern pan (of the scales)". Another name used in older astronomy texts, equivalent to "southern pan", was Lanx Australis.
...
Wikipedia