Formation of superstrong horizontal magnetic field in delta-type sunspot in radiation magnetohydrodynamic simulations
Formation of superstrong horizontal magnetic field in delta-type sunspot in radiation magnetohydrodynamic simulations
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DOI：
10.1093/mnras/staa2529
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发表时间：
2020-10-01
影响因子：
4.8
通讯作者：
Toriumi, S.
中科院分区：
文献类型：
--
作者：
Hotta, H.;Toriumi, S.
我们进行了一系列的辐射磁流体动力学模拟，以了解三角洲型太阳黑子中异常强的水平磁场的放大机制。在模拟中，我们成功地再现了三角型太阳黑子，并在正负极性之间的光桥中产生了超过6000 G的强磁场。研究结果表明：(1)强水平磁场放大的基本机制是由两个点的旋转引起的剪切运动。(2)强水平磁场保持无力状态。(3)磁场峰值强度不依赖于空间分辨率、顶边界条件和阿尔芬速度限制。旋转运动的根源是深对流区。因此，三角光斑光桥中的磁场可以被放大到光球中的超均分值。
We perform a series of radiative magnetohydrodynamic simulations to understand the amplification mechanism of the exceptionally strong horizontal magnetic field in delta-type sunspots. In the simulations, we succeed in reproducing the delta-type sunspot and resulting strong magnetic field exceeding 6000 G in a light bridge between the positive and negative polarities. Our conclusions in this study are summarized as follows: (1) The essential amplification mechanism of the strong horizontal magnetic field is the shear motion caused by the rotation of two spots. (2) The strong horizontal magnetic field remains the force-free state. (3) The peak strength of the magnetic fields does not depend on the spatial resolution, top boundary condition, or Alfven speed limit. The origin of the rotating motion is rooted in the deep convection zone. Therefore, the magnetic field in the delta-spot light bridge can be amplified to the superequipartition values in the photosphere.