Non-LTE analysis of pre-eruptive prominence plasma parameters’ effects on the Lyman β and Lyman γ lines with <i>Solar Orbiter</i> SPICE observations

ABSTRACT The first dedicated observation of an off-limb prominence by Solar Orbiter took place on 2023 April 15. Our aim is to determine the range of different physical parameters of this prominence and to examine how these parameters affect the formation of the Lyman $\beta$ and Lyman $\gamma$ lines of hydrogen. We have found a way to refine key physical parameters by observational data. We will test the method by this prominence observation. We generate 200 random non-local thermodynamic equilibrium models using these observational constraints and compute the Ly $\beta$ line and the Ly $\gamma$ line profiles. We use the Spectral Imaging of the Coronal Environment (SPICE) full-disc mosaic from 2023 November 13 to constrain the incident radiation. We present the parameters and results of 200 random models using parallel coordinate plots to explore how different parameters affect the results. This allows us to infer the key physical parameters (e.g. central pressure, column mass, and temperature gradient) that impact the formation of the Ly $\beta$ line and the Ly $\gamma$ line in this observation.