Luminosity calibration for OB stars from Hipparcos trigonometric parallaxes

Hipparcos trigonometric parallaxes and observational data for open clusters are used to determine the absolute magnitudes M-v of O and B stars of vari ous spectral subtypes and luminosity classes, including those with broadene d lines and hydrogen emission lines. The same data are used to derive a rel ation between M-v and the index beta of the Stromgren photometric system. T he resulting calibrations and the spectroscopic-parallax method are used to determine the distances to young open clusters. (C) 2001 MAIK "Naitka/Inte rperiodica".