Asymmetries and Broadenings of Spectral Lines in Strongly Charged Iron Produced during Solar Flares

Abstract

Abstract Spatially resolved spectroscopic observations show wing enhancements and broadening in extreme ultraviolet emission lines, particularly in hot iron lines. Various explanations ranging from plasma turbulence and magnetic perturbations, to nonthermal ion populations and multiple flows in unresolved structures have been proposed. In this work, we revisit the role of single loop plasma dynamics in spectral line shape by reproducing the wing enhancements of Fe xxiii and xxiv observed during a C-class solar flare using a single loop hydrodynamic model. We also run simulations with different loop lengths and the same beam parameters to investigate the role of loop length in line broadening and asymmetry. We find that the single loop model successfully reproduces line asymmetries and the loop length plays an important role in explaining some of the key observations such as the positive correlation between the Doppler shifts and line width, and broad but symmetric hot Fe lines.