Investigating the physics of the solar wind and its origin at the Sun using Solar Orbiter and Parker Solar Probe

在绕太阳运行的过程中，地球不断受到高能带电粒子的冲击，这种现象被称为太阳风。这种源源不断的物质外流来自日冕洞，即太阳大气(日冕)的区域，在对太阳的极端紫外线和X射线观测中，这些区域看起来很暗。尽管它的产生与太阳活动无关，是空间天气的一个关键驱动因素，这一现象可能对航天器和近地环境产生不利影响，但人们对太阳风的起源和演化及其与冕洞的关系知之甚少。日冕洞是一种非常安静、稳定、寿命长的特征，可以覆盖太阳表面的很大一部分，但更广泛的太阳物理界对这些特征的研究不足，而倾向于更活跃的现象。因此，关于日冕黑洞的形成和演化有许多重要的悬而未决的问题，包括为什么它们在某些波长(例如EUV和X射线)看起来很暗，而在另一些波长(例如莱曼-阿尔法)看起来很亮，它们的边界是如何演变的并与邻近的安静太阳区域相互作用。这些问题对空间天气研究和预报具有重大影响，回答这些问题将提高我们缓解空间天气对天基和地面基础设施影响的能力。最近发射的帕克太阳探测器和太阳轨道飞行器有望帮助揭示这些问题。这两个航天器都比以往任何时候都更接近太阳，携带着各种遥感和现场仪器，旨在以非常高的分辨率观察太阳，并在太阳风在太阳系的旅程中混淆之前探测它。这个项目的目的是利用这些新的天文台在比以前更高的空间和时间尺度上调查日冕洞，量化它们的演化和与周围安静的太阳的相互作用，并测量这种持续的相互作用如何影响释放到太阳系的太阳风。该项目将涉及与伦敦大学学院的几个团队密切合作，这些团队在太阳轨道器上安装了仪器，包括极端紫外线成像仪和太阳风分析仪，以及与参与空间天气预报和预报的科学家密切合作。

As it orbits the Sun, the Earth is constantly buffeted by highly energetic charged particles; a phenomenon known as the solar wind. This constant outflow of material originates in coronal holes, regions of the solar atmosphere (the corona) which appear dark in extreme ultraviolet and X-ray observations of the Sun. Although it is produced regardless of solar activity and is a key driver of space weather, a phenomenon which can adversely affect spacecraft and the near-Earth environment, the origins and evolution of the solar wind and its relationship to coronal holes are very poorly understood. Coronal holes are very quiet, stable, long-lived features that can cover significant fractions of the solar surface, that have been under-investigated by the wider solar physics community in favour of more active phenomena. As a result, there are many significant open questions regarding the formation and evolution of coronal holes, including why they appear dark in some wavelengths (e.g., EUV and X-ray) but bright in others (e.g., Lyman-alpha), and how their boundaries evolve and interact with neighbouring quiet Sun regions. These questions have significant implications for space weather research and forecasting, and answering them will improve our ability to mitigate against the effects of space weather on space-based and ground-based infrastructure.The recent launch of the Parker Solar Probe and Solar Orbiter spacecraft promises to help shed some light on these issues. Both spacecraft are travelling closer to the Sun than ever before, carrying a variety of remote-sensing and in-situ instrumentation designed to observe the Sun with very high resolution and probe the solar wind before it is mixed up on its journey through the solar system. The aim of this project is to use these new observatories to investigate coronal holes at higher spatial and temporal scales than before, quantifying their evolution and interaction with the surrounding quiet Sun, and measuring how this continuous interaction affects the solar wind released into the solar system. The project will involve working closely with several of the teams at UCL who have instruments onboard Solar Orbiter, including the Extreme Ultraviolet Imager and Solar Wind Analyser, as well as with scientists involved in space weather forecasting and prediction.