2013A&A...557A..13B

We present the first results of a comprehensive photometric O-star survey performed with a robotic twin refractor at the Universitaetssternwarte Bochum located near Cerro Armazones in Chile. For three high-mass stars, Pismis24-1, CPD-51°8946, and HD319702, we determined the period through the Lafler-Kinman algorithm and modelled the light curves within the framework of the Roche geometry. For Pismis24-1, a previously known eclipsing binary, we provide the first light curves and determined a photometric period of 2.36 days together with an orbital inclination of 61.8°. The best-fitting model solution to the light curves suggests a detached configuration. With a primary temperature of T₁=42520K we obtained the temperature of the secondary component as T₂=41500K. The CPD-51°8946 system is another known eclipsing binary for which we present a revised photometric period of 1.96 days with an orbital inclination of 58.4°. The system probably has a semi-detached configuration and a mass ratio q=M₁/M₂=2.8. If we adopt a primary temperature of T₁=34550K, we obtain T₂=21500K for the secondary component. The HD319702 system is a newly discovered eclipsing binary member of the young open cluster NGC6334. The system shows well-defined eclipses favouring a detached configuration with a period of 2.0-days and an orbital inclination of 67.5°. Combining our photometric result with the primary spectral type O8 III(f) (T₁=34000K) we derive a temperature of T₂=25200K for the secondary component.