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

太阳上发生的小范围变化发生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。这些变化被称为“前兆”，表明发生的过程可能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力的事件。强烈的太阳耀斑和日冕物质抛射造成重大的空间天气影响，对人类技术造成各种影响，包括对卫星和电网系统的破坏。该项目的更广泛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，以及为公众创建关于科学主题的教程。该项目的科学目标是确定前兆瞬变活动与太阳耀斑和日冕物质抛射之间的独特性和因果关系，以便更好地了解磁场重联和随后引发的太阳能量事件。实现这一目标的目标是(1)量化前兆在时间、空间和物理特征上相对于活动-平静时期类似现象的差异，从而巩固统计联系并确定物理唯一性，以及(2)研究前兆与随后事件的能量释放和喷发动力学之间的磁性联系，从而巩固因果关系。为了实现这些目标，研究人员将与NASA新资助的一项工作(HGI#80NSSC21K0738)合作，分析约1000个事件和匹配的事件-平静控制(包括耀斑-平静时期和CME-无耀斑事件)。利用光球矢量磁场的高阶矩分析和极端紫外线(EUV)发射的微分发射测量(DEM)分析，将研究事件前特征的时间行为、光球磁场背景、日冕动力学、温度和密度。已建立的统计分类代码和贝叶斯计数统计将用于评估与耀斑/CME相关的前兆和来自活动安静对照的瞬变之间的差异。将使用磁荷拓扑学(MCT)分析，通过非线性无力日冕模型验证，建立事件前亮化和暗淡与初始耀斑/喷发地点之间的磁性关联。该奖项反映了NSF的法定使命，并已通过使用基金会的智力优势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.