Dynamics of Complex Magnetic Fields: From the corona to the solar wind

该项目题为“复杂磁场的动力学：从日冕到太阳风”，是邓迪大学和达勒姆大学的研究人员就太阳大气中磁场的纠缠性质进行成功合作的延续。日冕，太阳的外层大气，是一个充满磁场的动态等离子体。这个磁场负责创造长期存在的结构，如日冕环，将日冕加热到数百万度的温度，以及爆炸性事件，如太阳耀斑和日冕物质抛射。这些强大的爆炸导致地球发生重大的空间天气事件，创造了北方和南方之光，但也有可能对从卫星和通信系统到电网和管道等工程系统造成破坏性的经济影响。越来越明显的是，预测空间气象事件的发生和影响不能依靠静态外推模型，而需要深入了解太阳磁场的动态行为。太阳日冕中复杂的三维磁场的细节是空间天气事件链的关键部分。与此同时，重要的是要了解这些磁结构在太阳风中向地球传播时的演变方式。该联合体旨在解决这些问题，作为科学界理解天体物理等离子体结构形成这一更广泛目标的一部分，联合体内的不同项目将侧重于事件链的不同方面。我们将解决的问题，如：我们如何才能最好地模拟随着时间的推移日冕磁结构的建立？在日冕中形成的扭曲的磁“通量绳”的性质是什么？当它们爆发并形成日冕物质抛射时，它们的结构是如何演变的？太阳风中不稳定的慢分量的来源在哪里？是什么机制使太阳的日冕如此之热？是什么控制着日冕磁场可以弛豫到的最低能量状态，从而控制着有多少能量可以用来加热等离子体？我们能预测相应的弛豫态的平衡结构吗？这些问题的共同之处是理解太阳日冕磁场中的动态多尺度过程的挑战。我们将使用数值模拟和数学建模相结合的方法来解决这些问题，主要是使用磁流体动力学的非线性偏微分方程。重要的是，建模将采用最新一代太阳望远镜的输入-我们的几个模型将直接“数据驱动”，观测结果将用于验证输出（从日冕磁场的全球模拟到对缓慢太阳风和地球磁云结构的预测）。结合起来，这些结果将有助于预测和解释日冕中的事件，并回答STFC的科学路线图挑战B：2（“太阳如何影响地球和太阳系其他部分的环境？），以及了解一些基本的等离子体物理过程，在整个宇宙中进行。

This project, entitled "Dynamics of Complex Magnetic Fields: From the corona to the solar wind'', is a continuation of a successful collaboration between the researchers of the Universities of Dundee and Durham on the entangled nature of magnetic fields in the solar atmosphere. The corona, the outer atmosphere of the Sun, is a dynamic plasma permeated by a magnetic field. This magnetic field is responsible for creating long-lived structures such as coronal loops, for heating the corona to its multi-million degree temperatures, and for explosive events such as solar flares and coronal mass ejections. These powerful explosions lead to major space weather events at Earth, creating the Northern and Southern lights but also having the potential for damaging economic impacts on engineered systems, ranging from satellites and communication systems to power grids and pipelines. It is becoming apparent that forecasting the occurrence and impact of space weather events cannot rely on static extrapolation models but requires a deep understanding of the dynamical behaviour of the Sun's magnetic field. Details of the complex, three-dimensional magnetic fields in the Sun's corona are a critical part of the space weather chain of events. At the same time, it is important to understand the manner in which these magnetic structures evolve in the solar wind as they are carried out towards Earth. This consortium aims to address these questions, as part of a wider goal in the scientific community of understanding the formation of structures in astrophysical plasmas.Different projects within the consortium will focus on different aspects of the chain of events. We will address problems such as: How can we best model the build-up of coronal magnetic structure over time? What is the nature of the twisted magnetic "flux ropes" that form in the corona, and how does their structure evolve as they erupt and form coronal mass ejections? Where is the source of the non-steady slow component of the solar wind? What is the mechanism that makes the Sun's corona so hot? What controls the lowest energy state to which the coronal magnetic field can relax, and therefore how much energy is available to heat the plasma? Can we predict the equilibrium structure of the corresponding relaxed states? Common to each of these questions is the challenge of understanding dynamical, multi-scale processes in the Sun's coronal magnetic field.We will use a combination of numerical simulations and mathematical modelling to tackle these questions, primarily using the non-linear partial differential equations of magnetohydrodynamics. Importantly, the modelling will take input from the latest generation of solar telescopes - several of our models will be directly "data-driven", and observations will be used to validate output (from global simulations of the coronal magnetic field to predictions of the slow solar wind and structure of magnetic clouds at Earth). Combined, the results will help to predict and explain events in the solar corona and to answer STFC's Science Roadmap Challenge B:2 ("How does the Sun influence the environment of the Earth and the rest of the Solar System?"), as well as to understand some of the basic plasma physical processes that go on throughout the Universe.