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Abstract
Most estimates of chemical composition come from the quantitative analysis and interpretation of spectra, frequently of emitting plasmas that are at extremely low density by laboratory standards. Spectral simulations of these plasmas must rely on a vast database of basic atomic and molecular cross sections and transition rates.Studying the spectral lines from astrophysical plasmas is more challenging in environments like kilo- nova ejecta where heavy elements are being produced through the rapid neutron capture process or r- process. Since properties of the emission are largely affected by opacities of the ejected material, enhance- ments in the available r-process data is important for neutron star merger modeling. However, given the complexity of the electronic structure of these heavy elements, considerable efforts are still needed to converge to a reliable set of atomic structure data. The aim of this work is to alleviate this situation for low charge state elements in the Os-like and Re-like isoelectronic sequence using the general-purpose relativistic atomic structure packages (GRASP0 and GRASP2K).
Also, kilonovae derive their energy from radioactive decay, including γ -rays, and γ -ray opacity highly depends on photoionization. In this regard, the AUTOSTRUCTURE code was used to compute the photoionization cross section for heavy elements like Tungsten ions.
Finally, we studied methods to generate a reliable dielectronic recombination (DR) database which is one of the most important processes in astrophysical plasmas. AUTOSTRUCTURE was adopted to compute DR rates for Li-like and Be-like Oxygen.