Beta Librae
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| Observation data Epoch J2000 |
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|---|---|
| Constellation (pronunciation) |
Libra |
| Right ascension | 15h 17m 00.47s |
| Declination | −09° 22' 58.3" |
| Apparent magnitude (V) | 2.61 |
| Characteristics | |
| Spectral type | B8V |
| U-B color index | −0.36 |
| B-V color index | −0.11 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | −35.2 km/s |
| Proper motion (μ) | RA: −0.096 mas/yr Dec.: −0.019 mas/yr |
| Parallax (π) | 20.38 ± 0.87 mas |
| Distance | 160 ± 7 ly (49 ± 2 pc) |
| Absolute magnitude (MV) | -0.84 |
| Details | |
| Radius | 1.2 R☉ |
| Luminosity | 130 L☉ |
| Temperature | 12,000 K |
| Metallicity | ? |
| Rotation | 230 km/s. |
| Age | ? years |
| Other designations | |
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Zubenelschemali, 27 Librae, HR 5685, BD -08°3935, HD 135742, GC 20539, SAO 140430, FK5 564, NSV 7009, HIP 74785.
Galactic Coordinates: l° 352.0, b° +39.2 |
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Beta Librae (β Lib / β Librae) is the brightest star in the constellation Libra. It also has the traditional name Zubeneschamali (pronounced /ˌzubənˌεʃːɨˈmeɪli/) and the Latin name Lanx Australis ("The southern scale of the balance"). The name Zubeneschamali is derived from the Arabic الزبن الشمالية (al-zuban al-šamāliyyah) meaning "The Northern Claw".[1]
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[edit] Description
Beta Librae is a blue dwarf star of spectral type B8 (main sequence star), a little less evolved than Sirius. It has apparent magnitude 2.7.
At a distance of 160 light years from Earth, it is about 130 times more luminous than the Sun and has a surface temperature of 12,000 kelvins, double that of the Sun. This high temperature produces light with a simple spectrum, making it ideal for examining the interstellar gas and dust between us and the star. Like many stars of its kind, it is spinning rapidly, over 100 times faster than the Sun. This type of hydrogen-fusing star often appears blue-white, but Beta Librae is often described as greenish, the only greenish star visible to the naked eye.[2]
The small periodic variations in the magnitude of the Beta Librae imply the presence of a companion star which is not directly observable from earth.[3]
[edit] History
According to Eratosthenes Beta Librae was observed to be brighter than Antares. Ptolemy, three hundred and fifty 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 with a variability of 0.03 of a magnitude.[1]
[edit] References
- ^ a b AAS (2006). LIBRA – A Balanced View. Auckland Astronomical Society. Retrieved on 2006-07-03.
- ^ Jim Kaler (2006). Zubeneschamali. Stars. Retrieved on 2006-07-03.
- ^ Mark Fisher (1999-2006). Zuben Elschemali. The Electronic Sky. Retrieved on 2006-07-03.
- HD 135742 -- Variable Star. SIMBAD Astronomical Database. Retrieved on 2007-01-22.
[edit] External links
Find more Arabic Star Names and their meanings at the following site:
- Moh'd Odeh (1998-2006). Arabic Star Names. Islamic Crescents' Observation Project. Retrieved on 2006-07-03.
