EFFECTIVE TEMPERATURE, BOLOMETRIC CORRECTION AND MASS CALIBRATION FOR O-F STARS

We discuss the determination of effective temperature, bolometric correction and surface gravity using Stromgren indices. We use synthetic colours to define the functional relationship over a wide range of surface gravity, and calibrate the relationship by means of stars with well-determined effective temperatures and surface gravities. The calibrations are presented as interpolation formulae, valid for O-F stars. We find that the latest evolutionary computations predict masses that agree with those from detached eclipsing binaries to within 7 per cent. We discuss the position of the zero-age main sequence from the models relative to that observed in two young open clusters. There is a serious discrepancy between the surface gravity calculated from model atmospheres and from evolutionary models.