Beta Librae

Beta Librae
Diagram showing star positions and boundaries of the Libra constellation and its surroundings
The position of β Librae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Libra
Right ascension 15h 17m 00.41382s[1]
Declination −09° 22′ 58.4919″[1]
Apparent magnitude (V) 2.61[2]
Characteristics
Evolutionary stage Main sequence
Spectral type B8 V[3]
U−B color index −0.359[4]
B−V color index −0.106[4]
Variable type Suspected
Astrometry
Radial velocity (Rv)−35.2[2] km/s
Proper motion (μ) RA: −98.10[1] mas/yr
Dec.: −19.65[1] mas/yr
Parallax (π)17.62 ± 0.16 mas[1]
Distance185 ± 2 ly
(56.8 ± 0.5 pc)
Absolute magnitude (MV)−1.16[5]
Details
Mass3.5+0.3
−0.2[3] M☉
Radius4.9[6] R☉
Luminosity130 L☉
Temperature12300[7] K
Metallicity [Fe/H]0.33[3] dex
Rotational velocity (v sin i)250[8] km/s
Age80+50
−40[3] Myr
Other designations
Zubeneschamali, Kiffa Australis, Lanx Borealis, β Lib, 27 Librae, BD-08° 3935, FK5 564, HD 135742, HIP 74785, HR 5685, NSV 7009, SAO 140430[9]
Database references
SIMBADdata

Beta Librae (β Librae, abbreviated Beta Lib, β Lib), formally named Zubeneschamali /zuːˌbɛnɛʃəˈmeɪli/,[10][11] is (despite its 'beta' designation) the brightest star in the zodiac constellation of Libra. From parallax measurements, its distance can be estimated as 185 light-years (57 parsecs) from the Sun.[1]

The apparent visual magnitude of this star is 2.6.[2] According to Eratosthenes, Beta Librae was observed to be brighter than Antares. Ptolemy, 350 years later, said it was as bright as Antares. The discrepancy may be due to Antares becoming brighter, but this is not known for certain. It could simply be caused by Beta Librae being a variable star, showing a present-day variability of 0.03 of a magnitude.[12]

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  3. ^ a b c d Cite error: The named reference apj736_2_89 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference apjs15_459 was invoked but never defined (see the help page).
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  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  11. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  12. ^ Cite error: The named reference Auk was invoked but never defined (see the help page).