Study of Particle Acceleration and Magnetic Field Structure in Solar Flares

太阳耀斑中粒子加速和磁场结构的研究

• 批准号: 12640240
• 负责人: SAKAO Taro
• 金额: $ 1.41万
• 依托单位: Institute of Space and Astronautical Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640240/
• 关键词: Solar Flares; Particle Acceleration; Hard X-ray Radiation; Magnetic Field Structure

By studying temporal evolution of solar flare hard X-ray footpoint sources with the Hard X-ray Telescope (HXT) aboard Yohkoh satellite, we have investigated magnetic field structure associated with flares and particle acceleration process(es). Amongst flares observed, a large flare which commenced on 14 July, 2000 has provided a unique opportunity to study hard X-ray footpoint sources in great detail. Analysis of this flare revealed a striking result that non-thermal (above 30 keV) footpoint sources show a pair of thin elongated ribbons which reminds one the so-called "two-ribbon structure" in H-alpha observations. This suggests that magnetic arcade structure, not just a single loop, should take part in solar flare energy release. Detailed analysis on the footpoint sources has indicated that magnetic shear decreases as the flare progresses, and that the sources tend to show harder spectra towards outer edges. These observational findings are expected to provide important clues for investigating particle acceleration mechanisms in flares. In addition to analyses of hard X-ray footpoint sources, theoretical studies, stimulated with the analyses, have been in progress with an attempt to understand solar flare energy release in the framework of 3-dimensional magnetic reconnection.

利用Yohkoh卫星上的硬x射线望远镜（HXT）研究太阳耀斑硬x射线足点源的时间演化，研究了与耀斑和粒子加速过程相关的磁场结构。在观测到的耀斑中，2000年7月14日开始的一次大耀斑为详细研究硬x射线足点源提供了独特的机会。对这一耀斑的分析揭示了一个惊人的结果：非热（高于30kev）的脚点源显示出一对细长的带状，这让人想起h - α观测中所谓的“双带状结构”。这表明磁拱廊结构，而不仅仅是一个单一的环，应该参与太阳耀斑的能量释放。对足点源的详细分析表明，随着耀斑的发展，磁切变减小，并且源的光谱向外缘呈现较硬的趋势。这些观测结果有望为研究耀斑中的粒子加速机制提供重要线索。除了对硬x射线足点源的分析外，理论研究也在进行中，试图在三维磁重联的框架下理解太阳耀斑的能量释放。

项目成果

Aschwanden, M.J., et al.: "Electron Trapping and Precipitation in Asymmetric Solar Flare Loops"Proc. IAU Symposium. 195. 375-376 (2000)

Aschwanden, M.J. 等人：“不对称太阳耀斑环中的电子捕获和沉淀”Proc。

Somov, B.V., et al.: "Modeling Large Solar Flares : Some General Principles"Adv. Sp. Res.. (To appear). (2003)

Somov, B.V. 等人：“大型太阳耀斑建模：一些一般原则”Adv.

Asai, A., Masuda, S., 他5名: "Fine Structure inside Flare Ribbons and its Temporal Evolution"COSPAR Colloquia Series. (印刷中). (2001)

Asai, A.、Masuda, S. 和其他 5 人：“耀斑丝带内部的精细结构及其时间演化”COSPAR 座谈会系列（2001 年）。

Aschwanden, M., 他4名: "Electron Trapping and Precipitation in Asymmetric Solar Flare Loops"Proc. IAU Symposium 195. 375-376 (2000)

Aschwanden, M. 和其他 4 人：“不对称太阳耀斑环中的电子捕获和沉淀”Proc. IAU 研讨会 195. 375-376 (2000)

Somov, B.V., et al.: "Magnetic Reconnection Scenario of the Bastille Day 2000 Flare"Astrophys. J.. 579. 863-873 (2002)

Somov, B.V. 等人：“2000 年巴士底日耀斑的磁重联情景”天体物理学。