Flare-productive active regions
Flare-productive active regions
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DOI：
10.1007/s41116-019-0019-7
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发表时间：
2019-04
影响因子：
20.9
通讯作者：
S. Toriumi;Haimin Wang
中科院分区：
文献类型：
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作者：
S. Toriumi;Haimin Wang
强烈的太阳耀斑和日冕物质抛射，在这里不仅定义为电磁辐射的爆发，而且定义为通过磁重联和等离子体不稳定性释放磁能的整个过程，都是从活动区（AR）发出的，在这些活动区中，高磁非势以各种各样的形式存在。本文从观测和理论两个方面对耀斑产生的AR的形成和演化进行了综述。本文首先介绍了太阳耀斑和太阳耀斑的起源，然后对耀斑前长期演化过程中的主要观测特征、耀斑发生时磁场的快速变化以及这些现象背后的物理机制进行了概述。我们对耀斑产生的AR的描述是：在湍流对流的作用下，内部上升的磁通量变形为复杂的结构，并获得了很高的非势能，当磁通量出现在表面时，建立了一个具有大自由磁能和螺旋度的AR，表现为太阳黑子、剪切极性反转线、磁通绳等;当足够的磁场能量积累时，耀斑就会发生，剧烈的日冕演化甚至会影响光球层中的磁场。我们表明，在过去的几十年里，观测仪器和建模能力的改善大大提高了我们的理解。最后，我们讨论了悬而未决的问题和未来的前景，并进一步扩大我们的范围，我们的知识可能的应用空间天气预报，历史上的极端事件，以及相应的恒星活动。
Strong solar flares and coronal mass ejections, here defined not only as the bursts of electromagnetic radiation but as the entire process in which magnetic energy is released through magnetic reconnection and plasma instability, emanate from active regions (ARs) in which high magnetic non-potentiality resides in a wide variety of forms. This review focuses on the formation and evolution of flare-productive ARs from both observational and theoretical points of view. Starting from a general introduction of the genesis of ARs and solar flares, we give an overview of the key observational features during the long-term evolution in the pre-flare state, the rapid changes in the magnetic field associated with the flare occurrence, and the physical mechanisms behind these phenomena. Our picture of flare-productive ARs is summarized as follows: subject to the turbulent convection, the rising magnetic flux in the interior deforms into a complex structure and gains high non-potentiality; as the flux appears on the surface, an AR with large free magnetic energy and helicity is built, which is represented by-sunspots, sheared polarity inversion lines, magnetic flux ropes, etc; the flare occurs when sufficient magnetic energy has accumulated, and the drastic coronal evolution affects magnetic fields even in the photosphere. We show that the improvement of observational instruments and modeling capabilities has significantly advanced our understanding in the last decades. Finally, we discuss the outstanding issues and future perspective and further broaden our scope to the possible applications of our knowledge to space-weather forecasting, extreme events in history, and corresponding stellar activities.