Large-scale 3D MHD simulation on the solar flux emergence and the small-scale dynamic features in an active region
Large-scale 3D MHD simulation on the solar flux emergence and the small-scale dynamic features in an active region
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DOI：
10.1051/0004-6361/201118009
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发表时间：
2012-01
期刊：
影响因子：
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通讯作者：
S. Toriumi;T. Yokoyama
中科院分区：
文献类型：
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作者：
S. Toriumi;T. Yokoyama
我们进行了三维磁流体力学模拟，研究了从太阳对流区-20,000公里处通过光球层和色球层到日冕的扭曲磁通量管的出现。初始管子的中间部分具有密度差，以促使浮力浮现。当管子接近表面时，由于管子前面的光球，它水平延伸并形成平坦的磁性结构。通过光球场的互换模式不稳定性，进一步涌现到日冕，最终在表面上建立了几个磁穹顶。这个三维实验的新之处在于，在光球层磁图上观测到了垂直磁性元素的多次分离事件，它们反映了交换不稳定。发现分离的元素聚集在活动区域的边缘。然后，这些聚集的元素表现出剪切运动。这些特征使人高度联想到活跃的区域观测。在以上模拟结果的基础上，我们提出了通量出现和活动区形成的理论图景，解释了观测特征，如光斑的多次分离和剪切运动。
We have performed a three-dimensional magnetohydrodynamic simulation to study the emergence of a twisted magnetic flux tube from -20,000 km of the solar convection zone to the corona through the photosphere and the chromosphere. The middle part of the initial tube is endowed with a density deficit to instigate a buoyant emergence. As the tube approaches the surface, it extends horizontally and makes a flat magnetic structure due to the photosphere ahead of the tube. Further emergence to the corona breaks out via the interchange-mode instability of the photospheric fields, and eventually several magnetic domes build up above the surface. What is new in this three-dimensional experiment is, multiple separation events of the vertical magnetic elements are observed in the photospheric magnetogram, and they reflect the interchange instability. Separated elements are found to gather at the edges of the active region. These gathered elements then show shearing motions. These characteristics are highly reminiscent of active region observations. On the basis of the simulation results above, we propose a theoretical picture of the flux emergence and the formation of an active region that explains the observational features, such as multiple separations of faculae and the shearing motion.