Henry Draper Catalogue
Regulus BC is 5,000 AU from Regulus A. They share a common proper motion and are thought to orbit each other. Designated Regulus B and Regulus C, the pair has Henry Draper Catalogue number HD 87884. The first is a K2V star, while the second is about M4V. The companion pair has an orbital period of about 600 years with a separation of 2.5" in 1942.