Solar and Magnetospheric Plasma Theory

太阳和磁层等离子体理论

基本信息

批准号：
ST/K000950/1
负责人：
Alan Hood
金额：
$ 95.88万
依托单位：
University of St Andrews
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FK000950%2F1
关键词：
Solar Magnetospheric Plasma Theory

项目摘要

The Solar and Magnetospheric Theory Group (SMTG) of the University of St Andrews will work on the fundamental physical processes occurring in the Sun's atmosphere and planetary magnetospheres. For example:i) How do sunspots form, evolve and decay? ii) Why is the Sun's outer atmosphere (the corona) over 100 times hotter than the visible surface of the Sun so that the gas is ionized and forms a plasma? iii) What causes the waves in the Sun's atmosphere and what can these waves tell us about the local conditions there? iv) How does the Sun's magnetic field evolve over days, months and years and how does it interact with the Earth? v) How are electrons accelerated during solar magnetic disturbances? vi) How do solar magnetic fields interact with each other?The answers to many of these key questions depend upon a range of expertise and the SMTG is in an excellent position to answer these questions. We study a wide variety of physical phenomena using mathematical modelling (a combination of fundamental theory, analytical models, computer simulations, forward modelling and observations). It is an integrated approach that is needed, i.e. a mixture of modelling methods and a comparison between observations from several satellite missions and the theoretical models. The topics we will investigate, using plasma theory, are: i) the emergence of new magnetic field from the solar interior, the formation and evolution of active regions, the formation of cool dense prominences and the evolution of the global magnetic field of the Sun, ii) the physical mechanisms through which magnetic fields break their connectivity, reconnect with neighbouring fieldlines and how particles are accelerated to high speeds, iii) the use of Magnetohydrodynamics (MHD) wave theory to deduce properties of the solar atmosphere and magnetic field (coronal seismology), iv) the physical mechanisms responsible for keeping the corona much hotter than the lower parts of the solar atmosphere (coronal heating), v) the coupling of the 3 distinct magnetospheric MHD waves and the physics of the coupling of planetary magnetospheres to their ionospheres. These phenomena obey physical laws that can be expressed as non-linear partial differential equations. However, what makes them distinct is that different phenomena require different dominant terms. Hence, the physical processes and the plasma response will be different in each case. For example, magnetic reconnection requires electrical resistance but MHD waves in general do not. Gravity is important in flux emergence and prominence formation, but for magnetic reconnection it is not. Particle acceleration in solar flares and the magnetosphere requires a kinetic (particle) description, while many of the others research areas do not. It is the rich complexity of the non-linear equations that makes them hard to solve and to determine what the key physical processes are responsible for each event. A most important research tool is the parallel computer formed by linking many commodity processors together. Then the simulation involves splitting the problem up into smaller parts that run on different processors at the same time (in parallel). Thus, our simulations are completed quicker. Hence, with a job that would require 10 years on single machine, will be completed in a couple of weeks on 512 processors. We address key issues in the STFC Science Roadmap, especially, how does the Sun affect the Earth? However, a detailed understanding of the physics of our research topics are important not only for the Sun, solar-like stars and space weather, but also for understanding such diverse astrophysical processes such as star formation in giant molecular clouds, the evolution of astrophysical discs around stars, black holes and in Active Galactic Nuclei, and the physics of winds and outflows from stellar to extragalactic scales.

圣安德鲁斯大学的太阳能和磁层理论组（SMTG）将在太阳大气和行星磁层中发生的基本物理过程。例如：i）黑子如何形成，发展和腐烂？ ii）为什么太阳的外部大气（电晕）比太阳的可见表面高100倍，以使气体被离子化并形成等离子体？ iii）是什么原因导致太阳大气中的海浪，这些波浪能告诉我们有关那里的当地情况的什么？ iv）太阳的磁场如何在几天，几个月和几年中演变，以及它如何与地球相互作用？ v）在太阳磁性干扰期间，电子如何加速？ vi）太阳能磁场如何相互作用？这些关键问题中的许多答案取决于一系列专业知识，而SMTG则在回答这些问题的情况下处于良好的位置。我们使用数学建模（基本理论，分析模型，计算机模拟，正向建模和观察结果）研究了各种各样的物理现象。这是一种需要的综合方法，即建模方法的混合物以及几个卫星任务的观察结果与理论模型之间的比较。我们将使用血浆理论进行研究的主题是：i）新磁场的出现，来自太阳内部的新磁场，活跃区域的形成和演变，凉爽致密的突出的形成以及太阳的全球磁场的演变，ii）物理机制，ii）磁场与附近的连通性，重新连接，以II的高度使用粒子，以使粒子的使用方式很高。磁水动力学（MHD）波理论，以推断太阳大气和磁场的性能（冠状动脉学）；电离层。这些现象遵守可以表示为非线性偏微分方程的物理定律。但是，使它们与众不同的是，不同的现象需要不同的主要术语。因此，在每种情况下，物理过程和血浆响应都会有所不同。例如，磁重新连接需要电阻，但通常不使用MHD波。重力在通量出现和突出形成中很重要，但是对于磁重新连接而言并不重要。太阳耀斑和磁层中的颗粒加速度需要动力学（粒子）描述，而其他许多研究区则不需要。非线性方程的丰富复杂性使它们难以解决并确定关键物理过程对每个事件负责。最重要的研究工具是将许多商品处理器连接在一起而形成的并行计算机。然后，模拟涉及将问题拆分为同时（并行）在不同处理器上运行的较小部分。因此，我们的模拟更快地完成。因此，有了一项需要在单个机器上10年的工作，将在512个处理器上几周内完成。我们解决了STFC科学路线图中的关键问题，尤其是太阳如何影响地球？但是，对我们研究主题物理的详细理解不仅对太阳，类似太阳能的恒星和太空天气都很重要，而且对于理解了诸如巨型分子云中的恒星形成等多样化的天体物理过程，围绕恒星周围的天体物理盘的演变，黑孔的演变，黑色的孔，黑色的和甲基分离的核和型号的物理量表，以及从starectic strag scrall stactact。