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，它塑造了星际空间和行星大气。了解控制太阳膨胀的潜在物理过程是理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进入太空，这种知识的重要性变得更加重要。具体地说，尽管几十年来一直致力于太阳风的观测和理论研究，但我们仍然远未就太阳风在哪里加速以及如何加速达成共识。对太阳风的研究通常采用两种完全不同的技术：对日光层中当地风的等离子体性质进行现场测量，以及对距离太阳表面大约1.5个太阳半径的区域进行遥感(光谱和成像)。然而，太阳风继续加速的1.5到4个太阳半径之间的日冕区域，大部分还没有被探测到。日全食事件提供了难得的、独特的机会来观测这一关键的日冕区域。这项研究合作背后的基本想法是利用最近和即将发生的日全食事件期间的日冕观测来获得该地区的太阳风参数的测量，其中许多参数将是此类测量中的第一次。日全食是一种独特的天文事件，能激发人们的想象力。该团队在公众宣传和通识教育工作方面取得了成功的记录，这些工作建立在这种轻松的吸引力基础上，以提高公众对科学研究的认识，并吸引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被聘用并接受培训，以参与这项研究，这项工作将成为该人论文的重要组成部分。本科生的参与将通过密歇根大学现有的本科生研究机会计划整合到密歇根大学的研究中，该项目不收取任何费用。这项研究项目的目的是调查1.5到4个太阳半径之间的日冕区，在那里太阳风继续加速，其电荷状态成分冻结在那里。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器。这项研究利用对铁电离连续阶段发出的可见线的日食观测来研究大范围的日冕。将使用线与连续体和线与线的强度比来构建铁冻结位置的地图。将测量处于带电状态的冻结状态，并将其与现场测量直接比较，从而将遥感和现场观测联系起来。诊断将把现有的基安蒂红酒光谱代码与用户定义的太阳风的速度、温度和密度结合起来。预报的谱线强度将与日食观测结果进行比较，输入的等离子体参数将被修改，直到达成一致。由此得到的太阳风等离子体参数经验模型将能够区分不同的候选风源区，并将为太阳风加热和加速模型提供约束。