SHINE: Exploring a New Technique for Measuring the Vector Magnetic Field in the Solar Corona

SHINE：探索测量日冕矢量磁场的新技术

• 批准号: 1358270
• 负责人: Svetlana Berdyugina
• 金额: $ 34.71万
• 依托单位: Predictive Science Incorporated
• 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: 2014-10-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1358270&HistoricalAwards=false
• 关键词: SHINE; Exploring; New; Technique; Measuring

Solar magnetism is what powers the solar wind and coronal mass ejections (CME) and it is the ultimate source of space weather. Forecasting space weather and the onset and acceleration of CMEs is a critical goal of solar and space physics. For modern society it is crucial to respond to geo-effective CMEs that can damage satellites or ground-based technology. Reliable forecast of geo-effective events requires knowledge of the coronal magnetic field within a few solar radii where its structure and variability affects space weather by modifying solar wind conditions and CME propagation. Unfortunately, measurements of the coronal magnetic field are inherently very difficult to make and, therefore, constitute a weak link in our understanding of many physical mechanisms at work in the heliosphere. This project introduces and explores a new technique for measuring both the strength and direction of the magnetic field in the solar corona. If successfully demonstrated, this will pave the way to synoptic (whole sun) measurements of the coronal fields with the upcoming NSF Major Research Equipment and Facilities Construction project, the Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope, ATST), which is scheduled to begin operation soon after the completion of this project. The project will promote hands-on Science Technology Engineering and Match (STEM) education through the NSF funded Akamai Workforce Initiative (AWI) for which the investigators on this project have served as mentors, participants and organizers. Three STEM AWI students will be involved in summer projects with hands-on experience in remote sensing technology. In addition, the project will fully enable one graduate student and partially enable a second student to complete their PhDs in solar and heliospheric physics. Furthermore, the new magnetometry technique that is developed under this grant will be integrated into the community coronal study tool FORWARD developed at the High Altitude Observatory of NSF's National Center for Atmospheric Research in Boulder, Colorado.The project concerns the development, implementation, and demonstration of a new technique for measuring coronal magnetic fields. It employs simultaneously linear spectropolarimetry of (i) the unsaturated Hanle effect in permitted lines, such as He I 1083 nm line being adsorbed from inter-planetary or comet matter in the hot corona and (ii) the saturated Hanle effect in the bright forbidden [Fe XIII] 1074.7 nm and [Si X] 1430 nm lines. The technique does not depend on the Zeeman effect in these lines. Observing these lines (quasi-) simultaneously can provide unambiguous measurements of the full magnetic vector in the corona. The goals of this project are to implement this new approach, determine specific requirements for observations and sensitivity limits, obtain a catalog of line polarization measurements, and infer vector images of magnetic fields in the solar corona. In addition to the He I line other permitted lines of neutral atomic and molecular species sublimating from Sun-grazing comets near their perihelion will be investigated. Observations will be carried out with the Scatter-Free Observatory for Limb Active Regions and Coronae (SOLARC), an IR imaging spectropolarimeter located on the summit of Haleakala, Maui. Furthermore, potential and nonlinear force-free field extrapolations as well as MHD-based magnetic field models will be computed and compared with magnetic vector maps inferred from observations.

太阳磁力是太阳风和日冕物质抛射(CME)的动力，也是空间天气的终极来源。预报空间天气和日冕物质抛射的开始和加速是太阳和空间物理学的一个重要目标。对现代社会来说，对可能损害卫星或地面技术的地球有效的CME作出反应至关重要。对地球效应事件的可靠预报需要了解几个太阳半径内的日冕磁场，而日冕磁场的结构和可变性通过改变太阳风条件和日冕物质抛射传播来影响空间天气。不幸的是，日冕磁场的测量本身就非常困难，因此，这是我们理解日光层中许多起作用的物理机制的薄弱环节。本项目介绍并探索了一种测量日冕磁场强度和方向的新技术。如果成功演示，这将为即将到来的美国国家科学基金会重大研究设备和设施建设项目--丹尼尔·K·井上太阳望远镜(DKIST，前身为先进技术太阳望远镜，ATST)--的日冕场天气(全太阳)测量铺平道路，该项目计划在该项目完成后不久开始运行。该项目将通过NSF资助的Akamai劳动力倡议(AWI)促进实践科学、技术、工程和匹配(STEM)教育，该项目的研究人员担任该项目的导师、参与者和组织者。三名STEM AWI学生将参与具有遥感技术实践经验的暑期项目。此外，该项目将完全使一名研究生能够完成他们在太阳和日球层物理学方面的博士学位，并使第二名学生能够部分完成他们的博士学位。此外，根据这笔赠款开发的新磁测量技术将被整合到位于科罗拉多州博尔德的美国国家科学基金会国家大气研究中心高海拔天文台开发的社区日冕研究工具中。该项目涉及测量日冕磁场的新技术的开发、实施和演示。它同时采用线性偏振光谱仪测量(I)允许谱线中的非饱和Hanle效应，如HeI1083 nm谱线被热晕中的行星际或彗星物质吸收，以及(Ii)明亮的[FeXIII]1074.7 nm和[SiX]1430 nm谱线中的饱和Hanle效应。这项技术并不依赖于这些线中的塞曼效应。同时(准)观测这些线可以提供日冕中完整磁矢量的明确测量结果。该项目的目标是实施这一新方法，确定对观测和灵敏度极限的具体要求，获得线偏振测量目录，并推断太阳日冕中磁场的矢量图像。除了He I谱线外，还将调查其他允许的中性原子和分子物种谱线，这些谱线是从近日点附近的掠日彗星升华而来的。将利用位于毛伊岛Haleakala山顶的无散射肢体活动区和日冕观测站(SOLARC)进行观测。此外，还将计算势场和非线性无力场外推以及基于MHD的磁场模型，并将其与从观测中推断的磁矢量图进行比较。