Collaborative Research: Large Scale Structures and Solar Wind Origin from Eclipse Observations of Coronal Lines

合作研究：日冕线日食观测中的大型结构和太阳风起源

• 批准号: 1255894
• 负责人: Shadia Habbal
• 金额: $ 24.83万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1255894&HistoricalAwards=false
• 关键词: Collaborative; Research; Large; Scale; Structures

The solar wind is the key component of the solar system that shapes the interplanetary space and planetary atmospheres. Understanding the underlying physical processes controlling its expansion is key to understanding the coupling of the Sun to the solar system. The importance of this knowledge is becoming all the more critical with our increased reliance on access to space by manned and unmanned missions. Specifically, despite decades of observational and theoretical studies devoted to the solar wind, we are still far from a consensus on where and how the solar wind is accelerated. The solar wind is usually studied with two completely different techniques: in-situ measurements of local wind plasma properties in the heliosphere, and remote sensing (spectroscopy and imaging) of regions closer than roughly 1.5 solar radii to the solar surface. The region of the solar corona between 1.5 and 4 solar radii, where the solar wind continues to accelerate, however, is largely unexplored. Total solar eclipse events offer rare, unique opportunities to obtain observations of this crucial region of the solar corona. The basic idea behind this research collaboration is to utilize observations of the solar corona during recent and upcoming total solar eclipse events to obtain measurements of solar wind parameters for this region, many of which will be first of its kind. Total solar eclipses are unique astronomical events that capture people's imagination. The team has a successful record of public outreach and general education efforts that build on this easy fascination to raise public awareness of scientific research and engage young people's interest in science. A graduate student at the University of Hawaii Institute for Astronomy will be hired and trained to participate in this research and this work will constitute a significant part of that person's dissertation. Undergraduate student participation will be integrated into the research at the University of Michigan through the existing Undergraduate Research Opportunities Program there at no cost to this project. This research project is aimed at investigating the coronal region between 1.5 and 4 solar radii, where the solar wind continues to accelerate and its charge state composition freezes-in. In this region the evolution of heavy ions becomes a direct probe of solar wind heating and acceleration processes. This research uses eclipse observations of visible lines emitted by consecutive stages of ionization of iron to study the large-scale corona. Line-to-continuum and line-to-line intensity ratios will be used to build a map of the iron freeze-in location. Frozen in charge states will be measured and directly compared to in-situ measurements, linking remote sensing and in-situ observations. Diagnostics will couple the existing CHIANTI spectral code with user-defined velocity, temperature, and density of the solar wind. Predicted line intensities will be compared to eclipse observations, and the input plasma parameters will be modified until agreement is reached. The resulting empirical model of solar wind plasma parameters will be able to discriminate between different candidate wind source regions and will provide a constraint for solar wind heating and acceleration models.

太阳风是太阳系的关键组成部分，它塑造了行星际空间和行星大气层。了解控制其膨胀的基本物理过程是了解太阳与太阳系耦合的关键。随着我们越来越依赖载人和无人飞行任务进入太空，这些知识的重要性变得更加重要。 具体来说，尽管对太阳风进行了数十年的观测和理论研究，但我们对于太阳风加速的地点和方式仍远未达成共识。 太阳风通常使用两种完全不同的技术进行研究：日光层中局部风等离子体特性的现场测量，以及对距离太阳表面大约 1.5 个太阳半径较近的区域进行遥感（光谱和成像）。然而，太阳风持续加速的日冕区域在 1.5 到 4 个太阳半径之间，大部分尚未被探索。 日全食事件为观测日冕这一关键区域提供了难得的、独特的机会。这项研究合作背后的基本理念是利用最近和即将到来的日全食事件期间的日冕观测来获得该地区太阳风参数的测量结果，其中许多参数将是首次。日全食是激发人们想象力的独特天文事件。 该团队在公众宣传和通识教育方面有着成功的记录，这些努力建立在这种简单的迷恋之上，以提高公众对科学研究的认识并激发年轻人对科学的兴趣。夏威夷大学天文学研究所的一名研究生将受聘并接受培训来参与这项研究，这项工作将构成该人论文的重要组成部分。 本科生的参与将通过现有的本科生研究机会计划纳入密歇根大学的研究，该项目无需支付任何费用。该研究项目旨在调查 1.5 至 4 个太阳半径之间的日冕区域，该区域太阳风持续加速，其电荷态成分冻结。在这个区域，重离子的演化成为太阳风加热和加速过程的直接探测。这项研究利用日食观测铁电离连续阶段发出的可见线来研究大尺度日冕。线与连续体和线与线强度比将用于构建铁冻结位置的地图。将测量冻结的电荷状态并直接与现场测量进行比较，将遥感和现场观测联系起来。诊断功能会将现有的 CHIANTI 光谱代码与用户定义的太阳风速度、温度和密度相结合。预测的线强度将与日食观测进行比较，并且输入的等离子体参数将被修改，直到达成一致。由此产生的太阳风等离子体参数的经验模型将能够区分不同的候选风源区域，并将为太阳风加热和加速模型提供约束。