Lambda Orionis is the star's Bayer designation. The traditional name Meissa derives from the ArabicAl-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 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 refers to the Arabic lunar mansion that includes this star and the two of Phi Orionis. In Chinese, 觜宿, 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
Properties
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 28 times the mass of the Sunand 10 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. Meissa is actually a double star with a companion at an angular separation of 4.41 arcseconds along a position angle of 43.12°. This fainter component is of magnitude 5.61 and it has a stellar classification of B0.5 V, making it a B-type main sequence star. There is an outlying component, Meissa C, which is an F-type main sequence star with a classification of F8 V. This star in turn may have a very low mass companion that is probably a brown dwarf.
Ring
Meissa is surrounded by a ring of nebulosity about 12 degrees across. It is thought to be the remains of a supernova explosion, now ionized by the ultraviolet radiation from Meissa itself and some of the surrounding hot stars.
Cluster
This star is the dominant member of a 5-million-year-old star-forming region known as the λ Orionis cluster, or Collinder 69. The intense ultraviolet energy being radiated by this star is creating the Sh2-264H II region in the neighboring volume of space, which in turn is surrounded by an expanding ring of cool gas that has an age of about 2–6 million years. The expansion of this gaseous ring may be explained by a former binary companion of Meissa that became a Type II supernova. Such an event would also explain the star's peculiar velocitywith respect to the center of the expanding ring, as the explosion and resulting mass loss could have kicked Meissa out of the system. A potential candidate for the supernova remnant is the neutron starGeminga. However, the last is unlikely given the distance between Geminga and the cluster.
