Electron‐Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. III. Si‐Sequence Ions: Si i , S iii , Ar v , Ca vii , and Fe xiii

Abstract

Photoionization cross sections, σPI, and electron-ion recombination rate coefficients, αR, for silicon-like ions are calculated. Calculations are carried out in the close coupling approximation using the R-matrix method. Each ion has a large number of bound states with n ≤ 10 and l ≤ 9: 433 for Ar V, 631 for Ca VII, and 1223 for Fe XIII. Both the partial photoionization cross sections leaving the core ion in the ground state and the total cross sections for ionization in the ground state as well as the excited core states are obtained for all bound states. The electron-ion recombination rates are obtained using a unified method, based on the close coupling R-matrix method, that incorporates both the radiative and dielectronic recombination processes in a self-consistent and unified manner. Total recombination rate coefficients are presented for a wide range of temperatures for practical applications. State-specific recombination rate coefficients for individual bound states are also presented. Results of Si I and S III, derived from earlier works, are also presented for completeness.