Lambda Orionis

Meissa 'mais@, designated Lambda Orionis (λ Orionis, abbreviated Lambda Ori, λ Ori) is a star in the constellation of Orion. It is a multiple star approximately 1,300ly away with a combined apparent magnitude of 3.33. The main components are an O8 giant star and a B-class main sequence star, separated by about 4′′. Despite Meissa being more luminous and only slightly further away than Rigel, it appears 3 magnitudes dimmer at visual wavelengths, with much of its radiation emitted in the ultraviolet due to its high temperature. Lambda Orionis is the star's Bayer designation. The traditional name Meissa derives from the Arabic Al-Maisan which means 'The Shining One'. Al-Maisan was originally used for Gamma Geminorum, but was mistakenly applied to Lambda Orionis and the name stuck. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Meissa for this star. It is now so entered in the IAU Catalog of Star Names. The original Arabic name for this star, Al Hakah (the source for another name for it, Heka) refers to the Arabic lunar mansion that includes this star and the two of Phi Orionis (Al Haḳʽah, 'a White Spot'). In Chinese, 觜宿 (Zī Sù), meaning Turtle Beak, refers to an asterism consisting of Meissa and both of Phi Orionis Consequently, the Chinese name for Meissa itself is 觜宿一 (Zī Sù yī, the First Star of Turtle Beak.) Meissa is a giant star with a stellar classification of O8 III and an apparent visible magnitude 3.54. It is an enormous star with about 26-28 times the mass of the Sun and 10-13 times the Sun's radius. The outer atmosphere has an effective temperature of around 35,000 K, giving it the characteristic blue glow of a hot O-type star. Meissa is a soft X-ray source with a luminosity of 1032 erg s−1 and peak emission in the energy range of 0.2–0.3 keV, which suggests the X-rays are probably being generated by the stellar wind.