EAGER: A First Principles Test of the Current Sheet Heating Hypothesis for the Solar Corona

EAGER：当前日冕片加热假说的第一原理测试

• 批准号: 1223727
• 负责人: Michael Goodman
• 金额: $ 7.5万
• 依托单位: West Virginia High Technology Consortium Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1223727&HistoricalAwards=false
• 关键词: EAGER; First; Principles; Test; Current

The Principal Investigator (PI) will test a long-standing hypothesis that solar coronal heating occurs in sub-resolution current sheets. The PI notes that theoretical estimates suggest that the thickness of such current sheets in the solar corona would be on the order of 100 meters or less, but there is no firm evidence that such sheets exist. These current sheets cannot be observed directly due to the inadequate spatial resolution of current observing technology. Since these sheets cannot yet be detected, the PI asserts that an indirect test for their existence would be to determine if magnetohydrodynamic (MHD) models can give rise to such phenomena from first principles physics, without in any way predisposing the MHD model to have current sheet solutions in the corona. The PI will create such a model and require that such solutions "arise naturally" from the intrinsic, nonlinear transport and radiation physics within the model. The PI's model will be designed to provide exact, self-consistent solutions for sub-resolution, heated, radiating current sheets under solar coronal conditions, and include realistic mathematical expressions for the radiative cooling rate and the anisotropic transport coefficients that determine solar coronal heating. If the PI finds his anticipated current sheet solutions, then these would constitute the first theoretical evidence for the existence of current sheets in the solar corona and would lend support to the current sheet coronal heating hypothesis. Such solutions would contribute to our fundamental understanding of radiation generation and anisotropic transport processes in current sheets and would permit more accurate multi-dimensional MHD simulations for increasing our understanding of magnetic reconnection, a phenomenon that is pervasive in space physics, astrophysics, and plasma physics. Magnetic reconnection is also a key phenomenon in the most energetic space weather events.

首席调查员(PI)将检验一个长期存在的假设，即太阳日冕加热发生在亚分辨率电流片中。PI指出，理论估计表明，日冕中这种电流片的厚度将在100米或更小的数量级，但没有确凿证据表明这种电流片的存在。由于当前观测技术的空间分辨率不足，无法直接观测到这些电流片。由于这些薄片还不能被检测到，PI断言，对它们存在的间接测试将是确定磁流体(MHD)模型是否可以从第一性原理物理中引起这种现象，而不会以任何方式使MHD模型在日冕中有当前的薄片解。PI将创建这样一个模型，并要求这样的解“自然地产生”于模型内的内在、非线性传输和辐射物理。PI的模型将被设计为在日冕条件下为次分辨率、加热的辐射电流片提供精确的、自洽的解，并包括辐射冷却速率和决定太阳日冕加热的各向异性传输系数的实际数学表达式。如果PI找到了他预期的电流片解决方案，那么这些将构成太阳日冕中存在电流片的第一个理论证据，并将支持当前的电流片日冕加热假说。这些解决方案将有助于我们对电流片中辐射产生和各向异性传输过程的基本理解，并将允许更准确的多维MHD模拟，以增加我们对磁重联的理解，磁重联是空间物理、天体物理和等离子体物理中普遍存在的一种现象。在能量最强的空间天气事件中，磁重联也是一个关键现象。