Physical and Wind Properties of OB-Stars

In this review, the physical and wind properties of OB-stars are discussed, with particular emphasis on metallicity dependence and recent results from the flames survey of massive stars. We summarize the relation between spectral type and T_eff, discuss the status quo of the “mass-discrepancy”, refer to the problem of “macro-turbulence” and comment on the distribution of rotational velocities. Observational constraints on the efficiency of rotational mixing are presented, and magnetic field measurements summarized. Wind properties are reviewed, and problems related to weak winds and wind-clumping highlighted.