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Tabit, Upsilon Orionis, 36 Orionis

A fourth magnitude star in the southern parts of Orion, southward of the point of Orion's Sword and close to Rigel in the sky. Its name comes from the Arabic for 'one who endures', and is not to be confused with Tabit, or Pi3 Orionis, which lies in the western parts of the same constellation. To exacerbate the confusion, Thabit is sometimes also called 'Tabit', and the two star names apparently share an etymology; it seems possible that a simple labelling error occurred at some point in history, and variants of the same name have now become attached to two otherwise unrelated stars.

Thabit is an intensely hot and massive blue star, lying more than 1,500 light years from the Solar System (and it is thus somewhat further away than Orion's more prominent stars). Thabit belongs to the class of pulsating variable stars known as Beta Cephei variables; the star physically contracts and expands over a period of some twelve hours, causing its brightness to increase and decrease accordingly.


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