ABSTRACT

This collaborative project aims to understand the heating mechanisms of the solar flare atmosphere. Solar flares are dramatic releases of energy which briefly increase X-ray emission from the Sun. They are believed to occur by rapidly converting magnetic energy, stored in the Sun's outer atmosphere, to heat, radiation, and super-sonic flows. It is a persistent puzzle that this conversion takes place on spatial scales so much smaller than the vast volume of energy being released. The team will conduct high-cadence, high-resolution, imaging and spectroscopic flare observations combining the Goode Solar Telescope (GST)?s unprecedented capabilities observing the flaring lower-atmosphere, and the upcoming high-cadence hard X-ray burst observations in Earth orbit, including a new very fast detector built in Montana and recently flown to the International Space Station. This combination will provide vital, new clues to the processes working on small scales to release large amounts of stored magnetic energy. The improved understanding of energy conversion will lead to a clearer understanding of solar flares and improvements in our ability to forecast flares and their effects on Earth. Graduate and undergraduate students will be supervised to conduct the research. The team will engage K-12 for education and public outreach.

To elucidate the mechanisms of heating the flare atmosphere, high-cadence, high-resolution, imaging and spectroscopic flare observations with the high-cadence (10 ms) hard X-ray burst observations will be used. The science questions are 1) what are the temporal scales of flare elementary bursts observed in multiple wavelengths? 2) what are the spatial scales of flare elementary bursts, in particular, where do hard X-ray radiation elementary bursts originate? And 3) what are the dynamical consequences of energy release by elementary bursts? They will investigate the temporal, spatial, and magnetic structures of elementary bursts, which are the basic units of flare energy release. The team will identify the temporal structures of elementary bursts (below 1 s) from both observations, and identify the spatial structures, locations, and magnetic environment of these bursts (of below 1 Mm). They will categorize the temporal and spectral behavior of flare elementary bursts with respect to the evolution stage of the flare and the magnetic environment hosting these bursts. They will also model the flare emissions observed in multiple wavelengths by multiple instruments and estimate the heating rates and their distribution in elementary bursts. Characterization of these properties will help improve flare modeling taking into account these scales and the implied viable heating mechanisms.

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.

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