ATOMIC DATA FOR OPACITY CALCULATIONS .19. THE MAGNESIUM ISOELECTRONIC SEQUENCE

As a contribution to the international Opacity Project, large numbers of multiplet term energies, f-values and photoionization cross sections have been calculated for those Mg-like ions of astrophysical interest: Mg I, Al II, Si III, S V, Ar VII, Ca IX and Fe XV. The present atomic data have been obtained in the close-coupling approximation with a modified version of the RMATRX computer program and recently developed asymptotic codes. We briefly discuss the new results, and representative comparisons with previous experimental and theoretical work are carried out. Emphasis is given to the large number of photoionization cross sections reported for the first time. We conclude that the statistical accuracy of the Opacity Project datasets for the Mg isoelectronic sequence is at least as high as that of any other set of data produced with the most elaborate methods available to date.