LMC X-3 Background

• Optical Photometry reveals 1.7 d orbital period

• Double-humped optical light curve characteristic of ellipsoidal variation

• 235 km/s amplitude velocity range suggests presence of bright accretion disk

• Long-term optical brightness variations

• Lack of X-ray eclipses indicates i < 70�

• Mco~7Msun (B3V companion)

• Strong black-hole candidate

• Long-term X-ray brightness variations presumed periodic with ~100 or 200 day period (Cowley et al. 1991 )