The mean absolute magnitude of the Am stars

Abstract

The mean absolute magnitude of the Am stars was determined from statistical parallaxes. The material comprises 137 Am stars all contained in the “Bright Stars Catalogue”. Separate solution based upon the tau and upsilon components were derived, and both are in excellent agreement. The final value was corrected for an average value of blanketing and for the effect of the invisible spectroscopic companions of the Am stars. The final result is: Mv = 0.9 mag and the mean probable error was estimated to be 0.3 mag. This result locates the Am stars 0.8 mag above the main sequence and 1.5 mag above the ZAMS. The duplicity and the blanketing correction therefore do not modify substantially previous conclusions on the place of the Am stars in the H-R diagram.