BU Canis Majoris was discovered to be a variable star when the Hipparcos data was analyzed. It was given its variable star designation in 1999.[7]
In 2021, BU Canis Majoris was found to be composed to two eclipsing binaries, totalling four stars. Both pairs are double-lined spectroscopic binary systems that form Algol-like eclipsing binaries.[5] The orbits of both systems are somewhat eccentric.[5] The brightness of the system decreases from 6.44 down to 6.53 during the primary eclipse.[8] It has a stellar classification of A0V,[4] which matches an A-type main-sequence star that is generating energy through hydrogen fusion at its core. In reality, however, all four stars are nearly equal in properties, and have masses from 3.1 to 3.4 solar masses.[5] The system is about 200 million years old.[5]
^ abCowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
^Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (January 1999). "The 74th Special Name-list of Variable Stars"(PDF). Information Bulletin on Variable Stars. 4659: 1–77. Bibcode:1999IBVS.4659....1K. Retrieved 3 January 2025.