Collaborative Research: SHINE--Using Photospheric Imprints of Coronal Currents to Understand Coronal Magnetic Structure

合作研究：SHINE——利用日冕电流的光球印记来了解日冕磁结构

• 批准号: 2302698
• 负责人: Stuart Gilchrist
• 金额: $ 10.76万
• 依托单位: Planetary Science Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2302698&HistoricalAwards=false
• 关键词: Collaborative; Research; SHINE; Using; Photospheric

Solar flares and coronal mass ejections (CMEs) drive the strongest disturbances in the solar system. These events are powered by the sudden release of magnetic energy stored in electric currents flowing in the coronal magnetic field. Basic questions about these currents remain: How do coronal currents evolve to become unstable in the lead up to such events? And how do these currents evolve to release magnetic energy during flares and CMEs? This project addresses these questions through modeling and analysis of coronal extreme ultra violet (EUV) images. The broader impacts include mentoring of undergraduate students and collaboration between US and Australian institutes. Outreach will be conducted for the Great American October 2023 and April 2024 solar eclipses. This project will employ Gauss’s separation method — which has a long heritage in terrestrial and planetary magnetism — to photospheric vector magnetograms (2D maps of the 3-component magnetic field) of solar active regions (ARs). The core idea of Gauss’s method is that the photospheric field can be unambiguously partitioned into three distinct parts, each with its own source: currents below the photosphere, currents above it, and currents passing through it. We refer to the part of the photospheric field due to coronal currents as the ”photospheric imprint” of these currents. Photospheric imprints, by themselves, cannot fully reveal the nature of coronal currents. Nonlinear, force-free field (NLFFF) extrapolations have previously been used to study coronal currents, but fields on these models’ bottom boundaries typically exhibit substantial inconsistencies with magnetogram fields. While both methods have limitations, combining them can substantially improve our under- standing of coronal currents. Accordingly, the project will exploit both approaches in case studies of flare- and CME-prone ARs, to investigate the structure and development of coronal currents. The team will analyze evolution in photospheric imprints and NLFFF models before and after flares/CMEs, and in quiet epochs to establish baseline rates of change. Coronal EUV images will also be studied for context.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

太阳耀斑和日冕物质抛射 (CME) 引发了太阳系中最强烈的扰动，这些事件是由日冕磁场中流动的电流中存储的磁能的突然释放所驱动的，关于这些电流的基本问题仍然存在：日冕是如何产生的。在此类事件发生之前，电流会变得不稳定？这些电流如何在耀斑和日冕物质抛射期间演化并释放磁能？该项目通过对日冕极紫外光进行建模和分析来解决这些问题。 (EUV) 图像。该项目将采用高斯分离方法，该方法具有悠久的历史。地球和行星磁学 — 太阳活动区 (AR) 的光球矢量磁图（三分量磁场的二维图）。高斯的方法是，光球场可以明确地分为三个不同的部分，每个部分都有自己的来源：光球层下方的电流、光球层上方的电流以及通过光球层电流的电流，我们将光球场的部分称为日冕电流。作为这些电流的“光球印记”，光球印记本身无法完全揭示非线性无力场（NLFFF）外推的性质。以前曾被用来研究日冕流，但这些模型底部边界上的场通常与磁图场表现出很大的不一致，尽管这两种方法都有局限性，但将它们结合起来可以大大提高我们对日冕流的理解。这两种方法都用于易发生耀斑和日冕物质抛射的 AR 案例研究，以研究日冕流的结构和发展，该团队将分析耀斑/日冕物质抛射前后的光球印记和 NLFFF 模型的演化，以及还将研究在安静时期建立基准变化率的日冕 EUV 图像。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。