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Birdun

Al Birdhaun, Epsilon Centauri

A blue star in the southern parts of the constellation Centaurus, Birdun lies a few degrees northwestward of Alpha Centauri and Agena, the two brightest stars in the constellation. The name Birdun comes from the Arabic Al Birdhaun (a form sometimes still used for the star's name) meaning 'the packhorse'.

Birdun is a blue giant star some 430 light years from the Sun, though the term 'giant' here is specifically a reference to the immense amount of energy radiated by the star rather than its physical size. Nonetheless Birdun is considerably larger than the Sun, with more than six times its diameter. Though young by stellar standards (it is thought to be some 16 million years old, less than 1% of the Sun's age) it emits about 18,000 times as much energy and is rapidly progressing through its life cycle.

This is a variable star of the Beta Cephei type, in which processes deep within the star cause energy to build up and be emitted in pulses from its surface. This process is relatively rapid, and in Birdun's case the star's magnitude pulses by 0.02 in periods of a little over four hours each.

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