The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

Abstract

The fields of 8 X-ray sources in the Magellanic Clouds believed to be Be/X-ray binaries have been searched for possible Be star counterparts. BVR and H alpha CCD imaging was employed to identify early type emission stars through colour indices and H alpha fluxes. Spectroscopy of 5 sources confirms the presence of H alpha emission in each case. Based on the positional coincidence of emission line objects with the X-ray sources, we identify Be star counterparts to the {ROSAT} sources RX J0032.9-7348, RX J0049.1-7250, RX J0054.9-7226 and RX J0101.0-7206, and to the recently discovered {ASCA} source AX J0051-722. We confirm the Be star nature of the counterpart to the {HEAO1} source H0544-66. In the field of the ROSAT source RX J0051.8-7231 we find that there are three possible counterparts, each showing evidence for H alpha emission. We find a close double in the error circle of the {EXOSAT} source EXO 0531.1-6609, each component of which could be a Be star associated with the X-ray source.