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Theta Centauri, 5 Centauri

The northernmost bright star in the constellation of Centaurus, Menkent lies southward of Spica in Virgo, across the trailing tail of Hydra that separates Virgo from Centaurus. Its northerly position means that this star was one of the few in Centaurus that were visible to John Flamsteed when he assigned his star numbers, making it one of only five in the entire constellation to have a modern Flamsteed designation (specifically, 5 Centauri). Menkent's northerly position also apparently accounts for its name, which seems to mean 'shoulder of the Centaur' (taking Men from the Arabic word for 'shoulder', and Kent from Kentaurus).

Lying just outside the plane of the Milky Way, Menkent shines in the skies of Earth with a magnitude of +2.1. The star is a little less that sixty light years from the Solar System, and its theoretical brightness at ten parsecs' distance (that is, its absolute magnitude) is +0.8.

Menkent is a relatively cool orange star that has consumed its reserves of hydrogen and evolved to derive its energy from the fusion of helium atoms. A giant star, it is more than ten times the diameter of the Sun, and far brighter. In the visible spectrum it is some forty times as luminous as the Sun, but in other wavelengths, especially X-rays, it generates even greater levels of energy.


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