Collaborative Research: Characterizing Energy Release and Flare Heating with High-Resolution Imaging and Spectral Observations and Modeling: Early DKIST Science

Solar flares are believed to be powered by magnetic energy released rapidly through magnetic reconnection. The total emission of a flare lasts for tens of minutes, evolving from the so-called impulsive rise phase through the gradual decay phase. Emission at the feet of each of the individual flare loops also often exhibit an impulsive rise followed by a prolonged decay. The goal of this project is to unravel the physical mechanisms that heat the solar atmosphere during flares. The project will combine numerical modeling with analysis of spatially and spectrally resolved observations to advance the understanding of flare heating mechanisms. Two graduate students will conduct the observational analysis and flare modeling, which will comprise a major part of their thesis projects. An improved understanding of flare physics will lead to advances in the accuracy of space weather forecasting. High-resolution observations reveal that a flare is a collection of energy release and heating-cooling events characterized by a multitude of flare loops in the corona and their foot-points in the chromosphere, which occur from the impulsive through the decay phase of the flare. To date the mechanisms heating the flaring atmosphere are not clear. This project takes advantage of several methodologies, leveraging the efficiency of the UFC 0D global modeling and the advanced capabilities of 1D numerical codes. The team will apply the UV Foot-point Calorimeter method (UFC) to modeling and analyzing multi-wavelength observations of flares, yielding the first-order heating rates in multiple flare loops. They will then use those heating rates to drive a one-dimensional radiative transfer model (RADYN) to simulate flaring atmosphere along the loop and test a few heating mechanisms in different phases of flare evolution. The results will be used to synthesize flare spectra observed in the chromosphere to be compared with high-resolution observations by IRIS and DKIST. This project will advance both models, enhancing their utility and efficiency to model flares and therefore maximize the science output of the large amount of flare data. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.