Nonequilibrium Ionization Effects on Synthetic Spectra in the AWSoM Solar Corona

Abstract

In this work, we combined AWSoM’s nonequilibrium ionization (NEI) calculations from Szente et al. with the synthetic spectral computations of SPECTRUM to predict nonequilibrium line intensities across the entire domain of the AWSoM 3D global model. We find that the resulting spectra are strongly affected by nonequilibrium effects in the fast-wind regions and streamer edges and that these effects propagate to narrowband images from SoHO/EIT, SECCHI/EUVI, and SDO/AIA. The dependence shows a different nature for each line observed, resulting in significant changes in line intensity, which need to be accounted for during plasma diagnostics. However, we also find that these effects depend on the local plasma properties, and that no single correction can be developed to account for nonequilibrium effects in observed spectra and images. With a comparison to observational data, we saw that the changes due to NEI, while significant, are not sufficient to account for the differences between Hinode/EIS spectra and AWSoM/SPECTRUM predictions.

Keywords

• Quiet Sun
• Solar corona
• Solar coronal lines
• Ionization
• Magnetohydrodynamical simulations
• High resolution spectroscopy