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，导致极其热的等离子体（数百万度开尔文）和高能电荷颗粒的光束。耀斑可以通过“太空天气”在许多方面影响地球和我们的太空环境。此外，许多小型耀斑样事件（称为纳米插花）的综合作用可能会导致热力阴影的存在。虽然广泛接受的是，耀斑是由于“磁重新连接”的过程释放了储存的磁能引起的，涉及磁场的快速重组，但有关如何释放能量和带电颗粒的加速，存在许多未解决的问题。众所周知，太阳能电晕具有高度动态性，充满了磁性波。尽管已经致力于了解波浪如何从太阳的内部传播到电晕，以及这些波如何在高度结构的冠状动力磁场中传播和消散，但对如何通过磁性重新连接在电晕本身中产生波的波浪知之甚少。我们在这里解决了这个问题，将通常分别处理的波和磁重新连接的研究汇总在一起。二键式磁场线被称为通量绳索的磁场线是自由磁能的储层，因此可能是太阳能燃料的位置。先前通过观察证实的理论研究表明，扭曲的通量绳的扭结不稳定性可能会触发储存的磁能的释放，加热等离子体和加速电子和离子。此外，将两个或多个通量绳合并为单个通量绳子也释放了磁能。这些过程的模拟表明，通常存在波和振荡，但是尚未研究这些波和振荡的特性。 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以及测试粒子和动力学模型，以遵循非热的能量颗粒。我们将探索生成的波浪和振荡，以及它们如何取决于磁性构型和外部驾驶。通过正向建模，我们将预测热和非热发射中的可观察到的特征，尤其是微波/无线电发射，这会引起磁场中能量电子的循环。这些结果将用于解释现有的观察结果，并指导未来的观察结果，例如使用Parker太阳能探头和平方公里阵列。