Galactic Coordinates: l° 352.0, b° +39.2
Beta Librae (β Lib / β Librae) is the brightest star in the constellation Libra. It also has the traditional name Zubeneschamali 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".(broken link)
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.
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.
HistoryAccording 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.
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