An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → giant star of → apparent visible magnitude 3.54 in the → Orion constellation. λ Ori is of → spectral type O8 III, has a mass of about 28 → solar masses, a size of about 10 → solar radii, and an → effective temperature of around 35,000 K. 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 is probably generated by the → stellar wind. Meissa is a member of the → Orion OB1 association. It is in fact a → double star with a → companion at an angular separation of 4.41 arcseconds. This fainter component has a magnitude of 5.61, is a → main sequence star of → spectral type B0.5 V. There is an outlying component, Meissa C, which is an F-type main sequence F8 V star. This star in turn may have a very low mass companion that is probably a brown dwarf. λ Ori, excites a fairly symmetric → H II region, Sh2-264 surrounding it. Many observational studies have found dark clouds external to this H II region.

Arabic al-maysan (مَیسان) "bright."