The spectra currently emerging from ground- and space-based facilities are of exceptional resolution and cover a broad range of wavelengths. To meaningfully analyse these spectra, astronomers utilise complex modelling codes to simulate the astrophysical observations. The main inputs to these codes are radiative and collisional atomic data to include energy levels, transition probabilities, collision rates for electron-impact excitation/ionisation, photoionisation and recombination. While some of the data can be obtained experimentally, they are usually of insufficient accuracy or limited to a small number of transitions. The R-Matrix approach is credited as one of the most powerful and reliable tools in calculating these atomic data. Recent and ongoing developments of the relativistic parallel DARC codes have enabled an order of magnitude advance in the accuracy of the atomic structure and subsequent collision calculations that are now feasible for lowly ionised high Z ions.
In 2017 the first gravitational wave from a binary neutron star merger (NSM) was detected and the ejected matter created a bright glow called a Kilonova via r-process nucleosynthesis. Disentangling r-process abundances from the broad spectra of NSM is a challenging task that demands a high degree of rigour in calculations of the ejecta opacity and the atomic calculations that underpin them. Recent publications by the group at QUB report on extensive relativistic atomic structure and electron-impact excitation collision calculations for the species Au I-III, Pt I-III, Sr II, Y II and Te I-III, which were subsequently used in collisional-radiative models to investigate line ratio diagnostics in NSM environments.