Advances in Atomic Data for Neutron-Capture Elements

TL;DR

This paper provides new atomic data for neutron-capture elements, enabling more accurate nebular abundance measurements and advancing understanding of s-process nucleosynthesis in planetary nebulae.

Contribution

It offers the first comprehensive calculations of photoionization, recombination, and charge transfer rates for key n-capture elements, filling critical data gaps.

Findings

Benchmarking against experimental data validates the calculations.

New atomic data will improve abundance determinations in planetary nebulae.

Enables detailed studies of s-process element enrichment.

Abstract

Neutron(n)-capture elements (atomic number Z>30), which can be produced in planetary nebula (PN) progenitor stars via s-process nucleosynthesis, have been detected in nearly 100 PNe. This demonstrates that nebular spectroscopy is a potentially powerful tool for studying the production and chemical evolution of trans-iron elements. However, significant challenges must be addressed before this goal can be achieved. One of the most substantial hurdles is the lack of atomic data for n-capture elements, particularly that needed to solve for their ionization equilibrium (and hence to convert ionic abundances to elemental abundances). To address this need, we have computed photoionization cross sections and radiative and dielectronic recombination rate coefficients for the first six ions of Se and Kr. The calculations were benchmarked against experimental photoionization cross section measurements. In addition, we computed charge transfer (CT) rate coefficients for ions of six n-capture elements. These efforts will enable the accurate determination of nebular Se and Kr abundances, allowing robust investigations of s-process enrichments in PNe.