Speaker
Description
First Name: Wenzhi
Last Name: Ruan
Affiliation: Max Planck Institute for Solar System Research
All Authors: Wenzhi Ruan, Damien Przybylski, Robert Cameron, Sami Solanki
Abstract: We present an extension of the MURaM solar/stellar atmosphere RMHD simulation code that improves the treatment of radiative heating and cooling, as well as the evolution of hydrogen level populations in the chromosphere. In the upper chromosphere, radiative energy exchange is dominated by the hydrogen Lyman-α transition, where the semi-transparent nature of this region in the Lyman-α line complicates accurate energy exchange calculations. In the previous MURaM implementation, radiative excitation and de-excitation in this transition were neglected, and radiative losses were computed using a pseudo–optically thin approximation. The new extension introduces a numerical radiative transfer treatment of the Lyman-α transition and self-consistently incorporates the resulting radiative heating, cooling, and level population evolution. The computed radiative losses and rates are compared with results from the non-LTE radiative transfer code Lightweaver, which employs a partial frequency redistribution (PRD) treatment. The comparison demonstrates that the extended MURaM code accurately reproduces the radiative losses and rates. Current work is applying the extended code to 3D simulations to compare results from the previous and updated versions, and to evaluate consistency with SO/SPICE observations.