Theory of Three-Dimensional Interchange Reconnection and the Dynamic Evolution of the Global Solar Coronal Magnetic Field Structure: A Mechanism for the Origin and Generation of the Slow Solar Wind.

[摘要] To understand the evolution of the solar corona and the generation of the solar wind, it is necessary to understand the structure and dynamics of the coronal magnetic field. Phenomenologically-based ``quasi-steady;; models have been developed under the assumption that the corona evolves as a time series of force-free equilibrium states determined by the normal-flux distribution at the photosphere. These models are successful at predicting the overall field polarity, global magnetic structures, and position of the heliospheric current sheet. However, the quasi-steady models cannot account for the observed bi-modal flow structure of the solar wind, nor several heliospheric observations with implications for the dynamics of the magnetic field. Motivated by these limitations, several researchers have proposed a fundamentally different paradigm for the evolution of the corona, the so-called Òinterchange modelÓ. Based on the interchange reconnection (IR) process, this model predicts a structure for the coronal magnetic field which substantially differs from the quasi-steady view.Strictly speaking, IR describes three-dimensional (3D) null point reconnection, in which closed bipolar flux reconnects with coronal hole flux opening into the heliosphere. More generally, the 3D null point reconnection mechanism is a direct consequence of the nested multi-polar field structure which occurs ubiquitously throughout the entire corona. This dissertation aims to rigorously investigate the 3D null point reconnection mechanism and the consequences thereof on the coronal environment. To that end, we present several related simulations that examine current sheet formation and stability, as well as the consequences of this type of reconnection on the structure and dynamics of the global magnetic field. We show the field topology remains smooth during the evolutions, incompatible with predictions of the initially proposed interchange model. In addition, we demonstrate dynamic effects of IR incompatible with the quasi-steady models. Therefore, we prove the necessity of a coronal description which includes fully-dynamic 3D magnetohydrodynamic effects. For sufficiently complex magnetic field structures and evolutions, the predicted dynamics of the quasi-steady and interchange models converge at the coronal hole boundaries. In the end, we offer the consequences of IR on the global coronal magnetic field as a generation mechanism for the slow solar wind.

[发布机构] University of Michigan

[效力级别] Magnetic Reconnection

[关键词] Solar Corona;Magnetic Reconnection;Solar Magnetic Fields;Science;Applied Physics