2005MNRAS.356..974N

From radial velocities determined in high signal-to-noise digital spectra, we report the discovery that the brightest component of the binary system HD 150136 is of spectral type O3. We also present the first double-lined orbital solution for this binary. Our radial velocities confirm the previously published spectroscopic orbital period of 2.6 d. Heii absorptions appear double at quadratures, but single lines of Nv and Niv visible in our spectra define a radial velocity orbit of higher semi-amplitude for the primary component than do the Heii lines. From our orbital analysis, we obtain minimum masses for the binary components of 27 and 18 M_☉. The neutral He absorptions apparently do not follow the orbital motion of any of the binary components, thus they most probably arise in a third star in the system.