Solar Models with Non–standard Chemical Composition

The OPAL monochromatic opacity tables are used to evaluate the impact of a non-standard chemical composition on solar models. A calibrated olar model with consistent diffusion including the effect of radiative forces and ionization on drift velocities is presented. It is shown that surface abundances are predicted to change slightly more than in the standard solar models. All elements included in the model settle at similar rates which is reflected in the relative variation in surface abundances ranging from 7.5% for calcium to 8.8% for argon. The structural difference between the consistent model and the standard model is small, with a maximum effect of 0.3% for the isothermal sound speed at the base of the convective zone. The settling of CNO is only marginally affected. Opacity profiles have also been calculated with varying abundances for volatile elements, for which the abundances are poorly known, and other selected elements. It is shown that if one allows a 10% variation of these elements individually one can expect a peak Rosseland mean opacity variation of 3% for oxygen, a little less 2% for Si and Ne, and around 1% for Mg and S in the radiative zone. Other light metals and volatile elements have no significant impact on the opacity.