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

在太阳耀斑和日冕物质抛射（CME）等强大而有影响力的事件发生之前，太阳会发生小规模的变化。这些变化被称为“前兆”，表明正在发生的过程可能会触发更大的能量事件。该项目调查前兆事件，以确定哪些事件可能导致这些有影响的事件。强大的太阳耀斑和日冕物质抛射会产生重大的空间天气影响，对人类技术造成多种影响，包括对卫星和电网系统的损害。该项目更广泛的影响包括了解这些重要的自然现象、培训本科生、支持早期职业研究人员以及为公众创建科学主题教程。该项目的科学目标是建立前兆瞬态活动与太阳耀斑和日冕物质抛射的独特性和因果关系，以便更好地了解磁重联和随后太阳高能事件的启动。实现这一目标的目标是（1）量化前兆与活动-安静时期类似现象在时间、空间和物理特征上的差异，从而巩固统计关联并识别物理独特性；（2）研究前兆与后续事件的能量释放和喷发动态之间的磁联系，从而巩固因果关系。为了实现这些目标，研究人员将与新资助的 NASA 项目 (HGI#80NSSC21K0738) 合作，分析约 1000 个事件并匹配事件安静控制（包括耀斑安静时期和无日冕物质抛射事件）。将使用光球矢量磁场的高阶矩分析和应用差分发射测量（DEM）分析的极紫外（EUV）发射来研究事件前特征的时间行为、光球磁背景、日冕动力学、温度和密度。已建立的统计分类器代码和贝叶斯计数统计将用于评估耀斑/日冕物质抛射相关前体和来自活动安静控制的瞬变之间的差异。事件前增亮和变暗与初始耀斑/喷发地点之间的磁关联将使用磁荷拓扑 (MCT) 分析建立，并通过非线性无力日冕模型进行验证。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.