Absolute magnitudes of OB and Be stars based on Hipparcos parallaxes

Absolute visual magnitudes of OB stars are determined from Hipparcos parallaxes using a sample of 1207 unreddened and 441 reddened stars of luminosity classes V-IV III, Ia and Iab-Ib-II. The value of total-to-selective extinction R for reddened stars was calculated from near-infrared photometry. The new M-v calibration is compared with existing calibrations. The visual absolute magnitudes of Be stars were obtained from a sample of 90 unreddened and 25 reddened stars. Generally, Be stars are brighter than B stars of the corresponding spectral types, in agreement with earlier results.