A New Heliospheric Field Model: Implications for Energetic Particles

新的日光层场模型：对高能粒子的影响

• 批准号: 0096664
• 负责人: Lennard Fisk
• 金额: $ 23.99万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-15 至 2005-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0096664&HistoricalAwards=false
• 关键词: New; Heliospheric; Field; Model; Implications

This is a proposal to explore the structure, dynamics, and evolution of the low solar corona. The main effort is theoretical analysis focused on four main questions: How does the heliospheric magnetic field reverse polarity from one solar cycle to the next? What controls the emergence of fast and slow solar wind? How is the dynamic evolution of the low corona tied to the structure and evolution of field and plasma in the heliosphere? For many decades the heliospheric magnetic field has been considered, on average, to execute a simple Archimedes spiral, typically termed the Parker spiral. . A magnetic field that is convected out radially with the solar wind, yet remains attached to a rigidly-rotating Sun will execute such a spiral pattern. Earlier work by these investigators showed how differential rotation in the photosphere and super-radial expansion of the solar wind not symmetric about the rotation axis lead to motion of heliospheric magnetic field footpoints near the solar wind source surface. These footpoint motions can cause strong systematic variations of the heliospheric magnetic field relative to a standard Archimedes spiral. The principles on which the new model was founded address a detailed connection between the dynamic evolution of the low corona and the heliospheric magnetic field. The new model has achieved some acceptance by the community, but many issues still remain. The investigators will test the correctness of the concepts by predicting their global consequences and comparing them to observations. To carry out these tests fully, idealized models must be generalized for the purpose of predictive modeling. The specific tasks to be carried out include: Obtain a more predictive model for footpoint motion that, in particular, does not rely on idealizations valid only during solar minimum; Use the generalized footpoint model to predict the global structure and evolution of the heliospheric magnetic field, and heliospheric plasma; Model the propagation of energetic particles and cosmic rays in the resultant heliospheric configurations and their evolution as the field is restructured during solar maximum.

这是一个探索低日冕的结构、动力学和演化的建议。 主要工作是集中在四个主要问题的理论分析：日光层磁场如何从一个太阳周期到下一个太阳周期反转极性？是什么控制着快速和缓慢太阳风的出现？低日冕的动态演化如何与日球层中的场和等离子体的结构和演化联系在一起？ 几十年来，日光层磁场平均被认为是一个简单的阿基米德螺旋，通常被称为帕克螺旋。.一个与太阳风径向对流的磁场，仍然附着在一个刚性旋转的太阳上，将执行这样的螺旋模式。 这些研究人员的早期工作表明，光球层的差异旋转和太阳风的超径向膨胀如何不对称于旋转轴，导致太阳风源表面附近日光层磁场足点的运动。 这些足点运动可以导致强烈的系统变化的日球磁场相对于标准阿基米德螺线。 新模型建立的原则是解决低日冕和日光层磁场的动态演化之间的详细联系。 新的模式已获得社区的一些接受，但仍存在许多问题。 研究人员将通过预测其全球后果并将其与观测结果进行比较来测试这些概念的正确性。 为了充分地进行这些测试，理想化的模型必须为了预测建模的目的而被泛化。 获得一个更具有预测性的足点运动模型，特别是不依赖于仅在太阳活动极小期有效的理想化;使用广义足点模型预测日光层磁场和日光层等离子体的全球结构和演变;模拟高能粒子和宇宙射线在日光层结构中的传播，以及它们在太阳活动极大期期间场重构时的演变。