Absolute magnitudes of OB and Be stars based on Hipparcos parallaxes – II

A new method of determining absolute visual magnitudes of early-type stars, based on averaging Hipparcos parallaxes ( ESA 1997 ) inside samples of the same spectrum and luminosity (Sp/L) classes, is proposed. The used sample consists of 6262 unreddened and reddened OB stars as well as 430 Be stars of luminosity classes Ia, Iab, Ib, II, III, IV and V. The colour excesses of the reddened stars have been calculated using the mean colour indices, according to the SIMBAD data base and the intrinsic ( B − V ) values calibrated for given Sp/L classes by Papaj, Wegner & Krełowski . The values of the total-to-selective extinction   R_V = A_V / E ( B − V )  for all reddened stars were calculated from the published near-infrared photometric measurements. The calculated visual magnitudes M_V of OB and Be stars are compared to those published by Wegner in Paper I, and the earlier determinations of Schmidt-Kaler. Generally, the new values of M_V agree well with those given in Paper I, except those for O stars which are systematically brighter than the earlier estimates. The mean absolute magnitudes published by Schmidt-Kaler are generally brighter (except OB stars of luminosity class V) than those determined in this paper.