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Mu1 Scorpii

One of the string of stars that forms the tail of Scorpius the Scorpion, curving across the Milky Way. This is one of a close optical pair of blue stars, the other being Mu2 Scorpii or Pipirima. The pair are separated by just five arcminutes, though in fact they are unrelated, falling some thirty or more light years apart on a close line of sight from Earth. In the Khoekhoe language of southern Africa, this pair are known as the 'eyes of the lion', and it from this that the name Xaimidimura comes (though formally the name belongs specifically to the primary star of the Mu1 Scorpii system).

Xamidimura is the blue star in the centre of this frame, with the similar star to the east (or left) being Pipirima or Mu2 Scorpii, which actually lies rather closer to the Sun. Together this optical double is known in parts of southern Africa as the 'eyes of the lion', the source of the name Xamidimura. Imagery provided by Aladin sky atlas

The Xamidimura system is a close binary, in which two blue main sequence stars orbit around one another at a distance of just 0.05 AU (that is, about six times the diameter of the Sun), so close that the stars are deformed by their proximity to one another, and matter flows from one star to the other. They complete their mutual orbit in a period of a little under thirty-five hours, and because of their alignment relative to Earth, this causes regular eclipses as one member of the pair passes across the other. The result is a variable star of the kind known as an eclipsing binary, in which the light of the star dims periodically as each eclipse occurs.


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