MAGHEAT: understanding energy deposition in the solar chromosphere

ongoing

The mechanisms that heat the solar chromosphere and corona, and that drive the solar dynamo, arguably remain some of the foremost questions in solar and stellar physics. Here, we focus on the question of how energy is transported and released in the solar chromosphere. During the past 20 years, numerical simulations of the chromosphere have been used, with increasing degree of sophistication, to validate various proposed heating mechanisms. These studies have gradually come to recognise that the mechanisms that are likely dominant may be different in different parts of chromospheric fine structures. To make progress, we therefore need constraints from highly resolved observational data. Recently, I implemented an inversion code that allows estimates of the overall chromospheric heating from spatially and spectrally resolved observational maps. Our results have unveiled very finely structured heating distributions with much larger amplitudes than the hitherto assumed canonical values. But a limitation is that this implementation cannot directly discriminate between the different heating mechanisms that have been proposed. The goal of MAGHEAT is to identify what mechanisms are heating the chromosphere, characterize the energy flux that is being released into the chromosphere and separate the contribution from each mechanism in active regions and flares. This goal is achievable with the combination of the proposed development of novel non-LTE inversion methods, new hybrid rMHD/particle simulations, and the availability of datasets with unprecedented high spatial resolution, large field-of-view, and high S/N ratio from DKIST, the Sunrise III mission, NASA’s IRIS satellite and updated instrumentation at the Swedish 1-m Solar Telescope. We will use observational data from these facilities to reconstruct new 3D empirical models of the photosphere and chromosphere, which will allow us to identify the mechanisms that are responsible for the energy deposition.