Upsilon Scorpii

Upsilon Scorpii (υ Sco, υ Scorpii) is a star located in the "stinger" of the southern zodiac constellation of Scorpius, the scorpion. It has the traditional name Lesath (alternative spellings Leschath, Lesuth), from Arabic las'a = "pass (or bite) of a poisonous animal"; but this is a miscorrection by Scaliger (a European astronomer who knew Arabic) for earlier "Alascha", which came from Arabic al laţkha = "the foggy patch", referring to the nearby open cluster M7. On the night sky it lies near the 1.6 magnitude star Lambda Scorpii, so the two form an optical pair that is sometimes called the "Cat's Eyes".

This star has apparent magnitude +2.7 and belongs to spectral class B2 IV, with the luminosity class of 'IV' indicating it is a subgiant star. From parallax measurements, it is approximately 580 light years from Earth. The star's luminosity is 12,300 times that of the Sun, while its surface temperature is 22,831 kelvins. The star has a radius of 6.1 times solar and 11 times the mass of the Sun.