Monthly Notices of the Royal Astronomical Society vol:302 issue:2 pages:245-252
beta Cen is a bright beta Cephei variable and has long been suspected to be a binary. Here we report interferometric observations with the 3.9-m Angle-Australian Telescope at a single epoch which show the star to be a binary with components separated by 15 milliarcsec and having approximately equal luminosities at 486 nm. We also present high-resolution spectra taken over five nights with the ESO CAT which show beta Cen to be a double-lined spectroscopic binary. We identify two pulsation frequencies in the primary. Further spectroscopic and interferometric studies of this double star should allow determination of its orbital parameters and component masses.