Effective temperature bolometric correction and mass calibration for O-F stars

Abstract

We discuss the determination of effective temperature, bolometric correction and surface gravity using Strömgren 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.