Chromospheric Dynamics and Line Formation

TL;DR

This paper discusses the complex dynamics of the solar chromosphere influenced by hydrodynamic waves and NLTE radiative transfer, highlighting the capabilities and limitations of current simulation models.

Contribution

It provides an introduction to NLTE radiation hydrodynamics equations and compares simulation results with observations, emphasizing the importance of 3D shock propagation.

Findings

1D codes capture strong brightenings well

Chromospheric dynamics are mainly driven by 3D shock waves

NLTE radiative transfer is crucial for understanding spectral line formation

Abstract

The solar chromosphere is very dynamic, due to the presence of large amplitude hydrodynamic waves. Their propagation is affected by NLTE radiative transport in strong spectral lines, which can in turn be used to diagnose the dynamics of the chromosphere. We give a basic introduction into the equations of NLTE radiation hydrodynamics and describe how they are solved in current numerical simulations. The comparison with observation shows that one-dimensional codes can describe strong brightenings quite well, but the overall chromospheric dynamics appears to be governed by three-dimensional shock propagation.