Absolute Magnitudes of Chemically Peculiar

The position of diierent kinds of CP stars of the upper Main Sequence (i.e. Am stars and the four categories of Ap stars: He-weak, HgMn, Si and SrCrEu) in the HR diagram is examined. Using only those stars having a parallax with a relative error smaller than 0.14 ((M v) 0:3) and an absolutely certain peculiarity, it is shown that their absolute magnitudes are similar to those obtained from CP stars in clusters. CP stars are scattered on the whole width of the Main Sequence band. However, the rapidly oscillating Ap stars seem slightly less evolved, hence less massive as a group, than their non-oscillating counterparts. The calibrations of the Strr omgren and Geneva indices in terms of M v have been reexamined in the light of the Hipparcos data for Am stars. A new calibration of the uvby system in absolute magnitude is proposed for both normal and Am stars. The calcium abundance in Am stars is examined as a function of their evolutionary state.