The True Relationship between "Precursor" Phenomena, Magnetic Topology, and Solar Energetic Events

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Small-scale changes occur on the Sun prior to the onset of powerful and impactful events like solar flares and coronal mass ejections (CMEs). These changes are known as a “precursor” and indicate processes occurring that may trigger the larger energetic events. This project investigates precursor events to determine which can lead to these impactful events. Powerful solar flares and CMEs create major space weather impacts that cause diverse effects for human technology, including damage to satellites and power grid systems. The broader impacts of the project include understanding these important natural phenomena, training undergraduate students, supporting an early career researcher, and creation of tutorials for the public on science topics. The science goal of the project is to establish the uniqueness and causal relationship of precursor transient activity to solar flares and CMEs in order to better understand magnetic reconnection and the subsequent initiation of solar energetic events. The objectives to meet this goal are (1) quantify the differences in temporal, spatial, and physical characteristics of precursors against similar phenomena during activity-quiet epochs, thus solidifying a statistical association and identifying physical uniqueness, and (2) investigate the magnetic connection between precursors and a subsequent event’s energy release and eruption dynamics, thus solidifying a causal relationship. To achieve these objectives the researchers will analyze ~1000 events and matched event-quiet controls (both flare-quiet epochs and CME-less flare events) in coordination with a newly-funded NASA effort (HGI#80NSSC21K0738). The pre-event signatures’ temporal behavior, photospheric magnetic context, coronal dynamics, temperature and density will be investigated using high-order moment analysis of their photospheric vector magnetic field and extreme ultraviolet (EUV) emission applying Differential Emission Measure (DEM) analysis. Established statistical classifier codes and Bayesian counting statistics will be used to evaluate the differences between flare/CME-related precursors and transients from activity-quiet controls. Magnetic association between pre-event brightenings and dimmings and the initial flare/eruption site will be established using Magnetic Charge Topology (MCT) analysis, validated by nonlinear force-free coronal models.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.