A New Heliospheric Field Model: Implications for Energetic Particles

这是一项探索低日冕结构、动力学和演化的建议。主要的工作是理论分析，集中在四个主要问题上：从一个太阳活动周期到下一个太阳活动周期，日球层磁场是如何反转极性的？是什么控制了快速和缓慢太阳风的出现？低日冕的动态演化与日球层磁场和等离子体的结构演化有何关系？几十年来，人们一直认为日球层磁场平均执行一个简单的阿基米德螺旋，通常称为帕克螺旋。磁场与太阳风呈放射状对流，但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。这些研究人员早期的工作表明，光球的微分旋转和太阳风的超径向膨胀不对称的旋转轴如何导致太阳风源表面附近的日球磁场脚点的运动。相对于标准的阿基米德螺旋，这些足点运动可以引起日球层磁场的强烈系统变化。建立新模型的原理详细地说明了低日冕的动态演化与日球层磁场之间的联系。这种新模式已经被社区所接受，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检验这些概念的正确性。为了充分进行这些测试，必须对理想化模型进行一般化，以便进行预测建模。具体任务包括：获得一个更具预测性的足点运动模型，特别是不依赖于仅在太阳极小期有效的理想化模型；利用广义足点模型预测日球磁场和日球等离子体的整体结构和演化；模拟高能粒子和宇宙射线在由此产生的日球层结构中的传播，以及它们在太阳极大期磁场重构时的演变。

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.