Delta Librae
Binary star in the constellation Libra
From Wikipedia, the free encyclopedia
Delta Librae, Latinized from δ Librae, is a variable star in the constellation Libra. It has the traditional name Zuben Elakribi, a variant of the traditional name of Gamma Librae.[11] With μ Virginis it forms one of the Akkadian lunar mansions Mulu-izi[12] (meaning "Man-of-fire").[13]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h 00m 58.34830s[1] |
| Declination | −08° 31′ 08.2104″[1] |
| Apparent magnitude (V) | 4.93[2] |
| Characteristics | |
| Spectral type | B9.5V[3] |
| U−B color index | −0.10[4] |
| B−V color index | +0.00[4] |
| Variable type | Algol eclipsing[5] |
| Astrometry | |
| Radial velocity (Rv) | −38.7±2[6] km/s |
| Proper motion (μ) | RA: −63.051[1] mas/yr Dec.: −6.024[1] mas/yr |
| Parallax (π) | 9.2824±0.4725 mas[1] |
| Distance | 350 ± 20 ly (108 ± 5 pc) |
| Absolute magnitude (MV) | +0.15[7] |
| Orbit | |
| Period (P) | 2.3273543 days[8] |
| Semi-major axis (a) | 12.73±0.34 mas[8] |
| Eccentricity (e) | 0.07[9] |
| Semi-amplitude (K1) (primary) | 76.6[9] km/s |
| Semi-amplitude (K2) (secondary) | 218.7[9] km/s |
| Details[8] | |
| δ Lib A | |
| Mass | 3.78±0.13 M☉ |
| Radius | 3.60±0.13 R☉ |
| Luminosity | 155+11 −10 L☉ |
| Temperature | 10,520±110 K |
| Age | 0.5[10] Gyr |
| δ Lib B | |
| Mass | 1.50±0.04 M☉ |
| Radius | 3.79±0.04 R☉ |
| Luminosity | 9.1+1.4 −1.2 L☉ |
| Temperature | 5,150±175 K |
| Other designations | |
| δ Lib, Zuben Elakribi, 19 Librae, BD−07°3938, HD 132742, HIP 73473, HR 5586, SAO 140270 | |
| Database references | |
| SIMBAD | data |
δ Librae is approximately 350 light years from the Earth and the primary, component A, belongs to the spectral class B9.5V, indicating it is a B-type main-sequence star. It is visible to the naked eye with an apparent visual magnitude of 4.93[2] and is moving closer to the Sun with a radial velocity of −39 km/s.[6] This is an Algol-like eclipsing binary star system, with a period of 2.3274 days and an eccentricity of 0.07.[9] Its apparent magnitude varies from 4.91 to 5.90.[15] The secondary is filling its Roche lobe and there is evidence of large-scale mass transfer in the past, with the secondary being more evolved than the primary despite now being less massive.[9]
Along with λ Tauri, it was one of the first stars on which rotational line broadening was observed, by Frank Schlesinger in 1911.[16]