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Evolution of coronal mass ejections from the sun to 1 AU: Property of magnetic field and a modified flux rope model.

机译：从太阳到1 AU的日冕物质抛射的演变：磁场性质和改进的磁通量绳模型。

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摘要

Coronal mass ejections (CMEs) are large scale eruptions originating on the Sun. They are the primary drivers of geomagnetic storms and other space weather disturbances that affect life and technology on the Earth. This dissertation presents a study of the dynamics of CMEs and their evolution from the Sun to the Earth, both observationally and theoretically, with the goal of helping to develop a space weather predictive capacity in the near future. The dynamics of CMEs is an important and unsolved science problem in solar physics, stellar physics, and plasma physics. The basic hypothesis adopted in this thesis is that the magnetic field structure underlying CMEs is a magnetic flux rope embedded within and expanding through an ambient plasma medium, the solar wind. The CME theory investigated in this thesis is formulated within the framework of ideal magnetohydrodynamics (MHD).;The CME acceleration and propagation to 1AU are quantitatively related to the properties of the solar source, such as the initial active region structure, the magnetic field magnitude, and properties of the interplanetary medium such as solar wind speed. The magnetic field and arrival times of CMEs at 1AU are calculated and compared with the in situ data. These results demonstrate that the magnetic field and arrival times of the CME at 1AU are not sensitive to the flux injection profile. The only critical parameter for predicting the magnitude of B and arrival time is the injected poloidal magnetic energy. This result has important implications for space weather prediction.;Also in this thesis work, the classical erupting flux rope (EFR) model is substantially enhnaced by including the expansion of CMEs in three orthogonal directions: the solar radial direction, transverse direction, and minor cross-sections. A system of four coupled second- order ordinary differential equations is derived to calculate the macroscopic 3D dynamics of CMEs. Computed theoretical results are quantitatively compared with available solar and in situ solar wind data, including observations from SOHO, STEREO, SDO, and ACE. It is shown that the theoretical solutions are in agreement with direct observational data for a number of different physical quantities that are measured from the Sun to 1 AU. This work demonstrates that the flux-rope hypothesis and the basic physics postulated in the EFR model lead to solutions that provide a manifestly correct description of the macroscopic CME dynamics in 3D. Consequently, this thesis work provides a new and rigorous theoretical framework for understanding the physics of CMEs.;In summary, this thesis greatly improves the quantitative understanding of CME propagation by combining both theoretical and observational studies. Future work will include investigation of a larger number of events to give a better statistical characterization of the results found in this observational study. A complete knowledge of the propagation of CMEs can help us to predict when a geomagnetic storm may occur with a lead time of tens of hours. Such a prediction can aid in mitigating severe space weather effects at the Earth.
机译：日冕物质抛射（CME）是起源于太阳的大规模喷发。它们是影响地球生命和技术的地磁风暴和其他空间天气干扰的主要驱动因素。本文从理论上和理论上对CME的动力学及其从太阳到地球的演化进行了研究，旨在帮助在不久的将来发展空间气象预报能力。 CME的动力学是太阳物理学，恒星物理学和等离子物理学中一个重要且尚未解决的科学问题。本论文采用的基本假设是，CME下方的磁场结构是嵌入在环境等离子体介质（即太阳风）中并在其中扩展的磁通量绳。本文研究的CME理论是在理想磁流体动力学（MHD）的框架内提出的。CME向1AU的加速和传播与太阳能的性质定量相关，如初始活性区域结构，磁场强度以及行星际介质的特性，例如太阳风速。计算出CME在1AU处的磁场和到达时间，并将其与原位数据进行比较。这些结果表明，CME在1AU处的磁场和到达时间对通量注入曲线不敏感。预测B的大小和到达时间的唯一关键参数是注入的极向磁能。这一结果对空间天气预报具有重要意义。此外，在本文工作中，通过包括CMEs在三个正交方向（太阳径向，横向和次要方向）的扩展，大大增强了经典喷发绳（EFR）模型。交叉区域。推导由四个耦合的二阶常微分方程组成的系统，以计算CME的宏观3D动力学。将计算出的理论结果与可用的太阳和原位太阳风数据进行定量比较，包括SOHO，STEREO，SDO和ACE的观测值。结果表明，理论解与从太阳到1 AU测得的许多不同物理量的直接观测数据一致。这项工作表明，在EFR模型中假设的磁通量假设和基本物理原理导致的解决方案为3D宏观CME动力学提供了明显正确的描述。因此，本文的工作为理解CMEs的物理性质提供了一个新的，严格的理论框架。综上所述，本论文通过理论与观察相结合，极大地提高了对CME传播的定量认识。未来的工作将包括对更多事件的调查，以便对该观察研究中的结果进行更好的统计表征。全面了解CME的传播可以帮助我们预测何时发生地磁风暴，前置时间为数十小时。这样的预测可以帮助减轻地球上严重的太空天气影响。

著录项

  • 作者

    Kunkel, Valbona.;

  • 作者单位

    George Mason University.;

  • 授予单位 George Mason University.;
  • 学科 Physics Astrophysics.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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