In apparent brightness it ranks, within Orion, admitting the higher published mean brightness of much more variable stars ranked above it, 35th.[citation needed]
Chi1 Orionis is an unrelated, yellow, main sequence star over two degrees away and far closer to the Sun.
χ2 Orionis has a B2 bright supergiant spectrum and is one of the standard B2 Ia stars.[7] It has been reported as having unusually narrow absorption lines and some weak emission lines and was included as one of the original Be stars.[8] It is no longer treated as a Be star since many supergiants show some emission features at high resolution and Be stars is usually defined to exclude supergiants.[9]
χ2 Orionis was listed as having likely small amplitude variability in photometry for the Third Catalogue of Stars measured in the Geneva Observatory Photometric System, specifically varying by 22 thousandths of a magnitude.[11] It was included in the General Catalogue of Variable Stars based on Hipparcos satellite photometry with a magnitude range (in the Hipparchos photometric system) of 4.68 - 4.72 and a period of 2.8 days.[12] A detailed study of the Hipparcos photometry confirmed the star as an α Cyg variable and gave the amplitude of variation as 0.057 magnitudes.[13]
^ abcdHR 2135, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line January 14, 2011.
^Andrillat, Y.; Jaschek, M.; Jaschek, C. (1994). "A study of Be stars in the wavelength region around Paschen 7". Astronomy and Astrophysics Supplement Series. 103: 135. Bibcode:1994A&AS..103..135A.
^"Light Curve". Hipparcos ESA. ESA. Retrieved 11 August 2022.
^Rufener, F.; Bartholdi, P. (1982). "List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry". Astronomy and Astrophysics Supplement Series. 48: 503. Bibcode:1982A&AS...48..503R.
^Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (1999). "The 74th Special Name-list of Variable Stars". Information Bulletin on Variable Stars. 4659: 1. Bibcode:1999IBVS.4659....1K.