Theoretical relations between model parameters and Metis observables for eruptive prominences and coronal mass ejections

Context. We investigate the behavior of the plasma in eruptive prominences and coronal mass ejections in characteristic physical conditions. Aims. We aim to demonstrate various relations between the plasma parameters and radiation properties relevant to Solar Orbiter and Metis observations. Methods. Our method is based on 2D non-local thermodynamic equilibrium (non-LTE) modeling of moving structures that are externally illuminated from the solar disk. We have focused on temperatures below 105 K and a range of gas pressures to investigate the opacity effects in the Lα line. Overall, we applied a large grid of isothermal and isobaric models. Results. Our results are presented in the form of various correlation plots showing relationships between the plasma parameters and radiation properties relevant to Metis observations. We also demonstrate the relative importance of radiative and collisional ionization of hydrogen and the ratio between radiative and collisional excitation of the Lα line. Our results point to the need to carry out optically thick non-LTE modeling for specific plasma conditions. The visible light (VL) emission was also obtained for the purposes of a comparison with the Metis data.