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Paper: Dielectronic Recombination Calculations for Si-like Ions and the S2+ Orion Nebula Abundance Conundrum
Volume: 515, Workshop on Astrophysical Opacities
Page: 269
Authors: Kaur, J.; Gorczyca, T.W.
Abstract: To model the spectral features observed in astronomical observations, we require accurate and complete descriptions of the relevant atomic processes occurring in stellar environments. Among them are the important dielectronic recombination (DR) and radiative recombination (RR) processes, which we have investigated for the entire silicon isoelectronic sequence. We use the perturbative, multi-configuration Breit–Pauli (MCBP) method, as implemented in the atomic structure and collision code AUTOSTRUCTURE, to compute the DR and RR rate coefficients for the ground and metastable initial levels of Si-like ions relevant to astrophysical and magnetic fusion plasmas. The DR results are compared with available experimental results and we find them to be in good overall agreement. In a further investigation we used the multi-configuration Hartree–Fock (MCHF) method to determine the low-lying resonance positions of S+. These play an important role in the low-temperature DR of S2+ in the Orion Nebula, where the rate coefficient is sensitive to the theoretically predicted resonance energy positions. This work is part of the development of a DR database required in the modeling of dynamic, finite density plasmas, and serves as a benchmark for measurements being carried out at national and international accelerator laboratories.
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