Speaker
Description
First Name: Arjun
Last Name: Kannan
Affiliation: Max Planck Institute for Solar System Research
All Authors: Arjun Kannan, Hardi Peter, Yajie Chen, Damien Przybylski
Abstract: The non-thermal line widths of spectral lines in the solar transition region and corona are considered to be a signature for different dynamical and heating processes. Surprisingly, the non-thermal motions in the corresponding extreme UV emission lines do not depend on the spatial resolution of the instrument. This indicates that the mechanism for the excessive broadening would operate either at a scale much smaller than currently resolvable or that it is hidden through gradients along the line of sight. 3D MHD models have so far failed to reproduce the observed non-thermal widths by a large margin. In this new study, we investigate recent high-resolution models of the quiet Sun using the MURaM code. The main goal is to see if, at sufficient resolution, the models match the observed values. For this, we synthesize several EUV emission lines and calculate their respective moments in order to obtain maps of the intensity, Doppler shift, and line width. These are then compared with real observations by convolving and rebinning the maps as per the resolution scale of the instrument. We find that the magnitude of the line broadening in the model gets close to the observations and that the correlation between intensity and non-thermal width is similar as in observed spectra. However, the dependence of the non-thermal widths on temperature and spatial resolution does not fully match the trends observed. This mismatch gives us the possibility to point to the weaknesses of the models and will hopefully allow us to provide suggestions to further improve the already good models.