Steady-State Heating of Diffuse Coronal Plasma in a Solar Active Region

TL;DR

This study combines 3D magnetic modeling with microwave and EUV observations to identify a steady-state heating process in a solar active region's corona, revealing insights into coronal temperature maintenance.

Contribution

It introduces a validated magneto-thermal model of an active region that supports steady-state heating, integrating multiple observational modalities.

Findings

Best thermal model indicates high-frequency energy release episodes.

Elemental abundances align with standard coronal values.

No significant deviations found in elemental composition.

Abstract

Solar corona is much hotter than lower layers of the solar atmosphere-photosphere and chromosphere. The coronal temperature is up to 1MK in quiet sun areas, while up to several MK in active regions, which implies a key role of magnetic field in coronal heating. This means that understanding coronal heating requires reliable modeling of the underlying three-dimensional (3D) magnetic structure of an active region validated by observations. Here we employ synergy between 3D modeling, optically thick gyroresonant microwave emission, and optically thin EUV emission to (i) obtain and validate the best magneto-thermal model of the active region and (ii) disentangle various components of the EUV emission known as diffuse component, bright loops, open field regions, and "moss" component produced at the transition region. Surprisingly, the best thermal model corresponds to high-frequency energy release episodes, similar to a steady-state heating. Our analysis did not reveal significant deviations of the elemental abundances from the standard coronal values.