Observational Studies of Early-type Binary Stars: MP Centauri

We present photometric and spectroscopic data on the early-type binary MP Centauri. The photometric data are analyzed simultaneously with radial velocities to derive preliminary absolute dimensions for the binary components. Analysis of the spectra shows that the stars rotate synchronously and that the line of sight to the system crosses two kinematically sharp and well-separated interstellar reddening sources. It is shown that MP Cen consists of a B3 primary with M_1 = 11.4 +/- 0.4 M_sun, R_1 = 7.7 +/- 0.1 R_sun and a lobe-filling B6-B7 secondary with M_2 = 4.4 +/- 0.2 M_sun, R_2 = 6.6 +/- 0.1 R_sun