Lambda Scorpii, 35 Scorpii

The star that marks the end of the Scorpion's stinger, Shaula is (despite its 'Lambda' designation) the second brightest of Scorpius' stars after Antares. Its brightness is variable, but it is conventionally the twenty-sixth brightest star in the sky, and can at times exceed the magnitude of Bellatrix in Orion.

The Shaula system consists of two stellar objects orbiting the primary blue subgiant star. One of these companions is another blue star following a long orbit taking more than1,000 days to complete. The other is a T Tauri star; a star extremely early in its formation having barely progressed past its protostar stage. Indeed the entire system is extremely young by stellar standards, and even the primary is probably no more than fifteen million years old (or about 0.3% of the age of the Sun). Shaula's variable magnitude is in part explained by its triple structure, but in addition the primary star is a Beta Cephei pulsating variable, whose intrinsic luminosity shows rapid changes of its own.

The distance of Shaula from the Sun has proved difficult to calculate, perhaps in part due to its triple structure, with estimated distances varying from about 240 light years out to 700 light years or more. The most accurate available figure for its distance is probably some 365 light years.


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