Delta Librae

δ Librae

A light curve for Delta Librae, adapted from Shobbrook (2005)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Libra
Right ascension 15h 00m 58.34830s[2]
Declination −08° 31′ 08.2104″[2]
Apparent magnitude (V) 4.93[3]
Characteristics
Spectral type B9.5V[4]
U−B color index –0.10[5]
B−V color index +0.00[5]
Variable type Eclipsing binary of Algol type (EA/SD)[6]
Astrometry
Radial velocity (Rv)−38.7±2[7] km/s
Proper motion (μ) RA: −63.051[2] mas/yr
Dec.: −6.024[2] mas/yr
Parallax (π)9.2824 ± 0.4725 mas[2]
Distance350 ± 20 ly
(108 ± 5 pc)
Absolute magnitude (MV)+0.15[8]
Orbit[9]
Period (P)2.3274 d
Eccentricity (e)0.07
Semi-amplitude (K1)
(primary)		76.6 km/s
Semi-amplitude (K2)
(secondary)		218.7 km/s
Details
δ Lib A
Mass4.9±0.2[9] M☉
Radius3.94[10] R☉
Luminosity86[8] L☉
Temperature8800[10] K
Age0.5[10] Gyr
δ Lib B
Mass1.7±0.2[9] M☉
Other designations
δ Lib, Zuben Elakribi, 19 Librae, BD–07°3938, HD 132742, HIP 73473, HR 5586, SAO 140270
Database references
SIMBADdata

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]).

δ Librae is approximately 300 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[3] and is moving closer to the Sun with a radial velocity of −39 km/s.[7] 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 4.91m to 5.9m.[14] The secondary is filling its Roche lobe and there is evidence of large-scale mass transfer in the past, with the star being more evolved than the primary.[9]

Along with λ Tauri, it was one of the first stars on which rotational line broadening[15] was observed, by Frank Schlesinger in 1911.

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  3. ^ a b Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
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  5. ^ a b Cite error: The named reference UBV was invoked but never defined (see the help page).
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  7. ^ a b Cite error: The named reference GCRV was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  9. ^ a b c d e Cite error: The named reference Tomkin1978 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Rhee was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference ACII was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Allen was invoked but never defined (see the help page).
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  14. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference test was invoked but never defined (see the help page).