On the effective temperatures, surface gravities, and optical region fluxes of the CP stars

We determined effective temperatures and surface gravities for 17 magnetic Chemically Peculiar (mCP) stars by comparing optical region spectrophotomet ry and H gamma profiles with the predictions of ATLAS9 model atmospheres. A lthough solar composition models can fit the energy distributions of the no rmal and many Mercury-Manganese stars, they cannot match the optical energy distributions of the mCP stars, especially the lambda 5200 broad, continuu m regions. The role of metallicity and microturbulence to provide appropria te energy distributions which fit those observed for the mCP stars is inves tigated. Using metal-rich models with the opacity distribution functions fo r microturbulent velocities of 4 and 8 km s(-1), their lambda 5200 broad, c ontinuum features are often fit as part of this process. For some stars it is impossible to fit simultaneously both this feature and the line blanketi ng in the H gamma region. This suggests that this continuum feature is prod uced by elements other than those which contribute most of the general line blanketing. A systematic difference in the temperatures found by the photo metric and spectrophotometric approaches is discovered for the hotter mCP s tars. An investigation of 10 Mercury-Manganese stars shows a similar effect . This may be due to the photospheric compositions becoming less solar with increasing temperature.