权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Reconnection-driven waves and oscillations in the flaring solar corona

耀斑日冕中重新连接驱动的波和振荡

基本信息

批准号：
ST/T00035X/1
负责人：
Philippa Browning
金额：
$ 47.64万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FT00035X%2F1
关键词：
Reconnection driven waves oscillations flaring

项目摘要

Solar flares are the most powerful explosions in the solar system, resulting in extremely hot plasma (tens of millions of degrees Kelvin) and beams of highly-energetic charged particles. Flares can affect the Earth and our space environment in many ways, through "space weather". Furthermore, the existence of a hot corona is likely to result from the combined effect of many small flare-like events known as nanoflares. Whilst it is widely accepted that flares are caused by a release of stored magnetic energy through the process of "magnetic reconnection", involving rapid restructuring of the magnetic field, there are many unanswered questions about how energy is released and charged particles are accelerated. It is known that the solar corona is highly dynamic and is full of magnetic waves. Whilst much attention has been devoted to understanding how waves may propagate from the interior of the Sun to the corona, and to how these waves propagate and dissipate in the highly-structured coronal magnetic field, much less is known about how waves may be generated in the corona itself by magnetic reconnection. We address this question here, bringing together the study of waves and magnetic reconnection which are usually treated separately.Twisted bundles of magnetic field lines known as flux ropes are reservoirs of free magnetic energy, and are thus likely sites for solar flares. Previous theoretical studies, confirmed by observations, have shown that the kink instability of twisted flux rope may trigger a release of stored magnetic energy, heating the plasma and accelerating electrons and ions. Furthermore, merging of two or more flux ropes into a single flux rope also releases magnetic energy. Simulations of these processes show that waves and oscillations are usually present, but the properties of these waves and oscillations have not been investigated. We will conduct advanced numerical simulations of energy release in twisted magnetic flux ropes in configurations relevant to solar flares (merger of two flux ropes, creation and merger of flux ropes within a large-scale current sheet, kink instability of a single flux rope, avalanches of heating triggered by one unstable twisted thread), coupling magnetohydrodynamics to model the large-scale magnetic evolution and test-particles and kinetic models to follow the non-thermal energetic particles. We will explore the waves and oscillations which are generated, and how these depend on the magnetic configuration and the external driving. By forward modelling, we will predict observable signatures in thermal and non-thermal emission, particularly microwave/radio emission arising fromn gyration of the energetic electrons in the magnetic fields. These results will be used to interpret existing observations, and to guide future observations, for example with Parker Solar Probe and the Square Kilometre Array.

太阳耀斑是太阳系中最强大的爆炸，导致极热的等离子体（数千万开尔文）和高能带电粒子束。耀斑可以通过“空间天气”以多种方式影响地球和我们的空间环境。此外，热日冕的存在很可能是由许多被称为纳米耀斑的小型耀斑事件的综合效应造成的。虽然人们普遍认为耀斑是由通过“磁重联”过程释放储存的磁能引起的，涉及磁场的快速重组，但关于能量如何释放和带电粒子如何加速还有许多未回答的问题。众所周知，日冕是高度动态的，充满了磁波。虽然人们一直致力于了解波如何从太阳内部传播到日冕，以及这些波如何在高度结构化的日冕磁场中传播和消散，但对日冕本身如何通过磁场重联产生波的了解要少得多。我们在这里解决这个问题，把通常分开处理的波和磁场重联的研究结合起来。被称为通量绳的磁场线扭曲束是自由磁能的储存器，因此很可能是太阳耀斑的发生地。先前的理论研究，经观测证实，已经表明扭曲磁通绳的扭结不稳定性可能会触发储存的磁能的释放，加热等离子体并加速电子和离子。此外，将两个或更多个通量绳合并成单个通量绳也释放磁能。这些过程的模拟表明，波和振荡通常是存在的，但这些波和振荡的性质还没有被调查。我们将进行先进的数值模拟的能量释放在扭曲的磁通绳的配置有关的太阳耀斑（两个磁通绳的合并，大规模电流片内磁通绳的产生和合并，单个磁通绳的扭结不稳定性，由一个不稳定的扭曲线触发的加热雪崩），耦合磁流体动力学来模拟大尺度磁演化和测试粒子以及动力学模型来跟踪非热高能粒子。我们将探讨产生的波和振荡，以及这些如何取决于磁结构和外部驱动。通过正演模拟，我们将预测可观察到的签名在热和非热发射，特别是微波/无线电发射所产生的高能电子在磁场中的回旋。这些结果将用于解释现有的观测结果，并指导未来的观测，例如帕克太阳探测器和平方公里阵列。