Lorentz Force: A Possible Driving Force for Sunspot Rotation
Lorentz Force: A Possible Driving Force for Sunspot Rotation
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DOI：
10.1007/s11207-008-9236-2
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发表时间：
2008-07
期刊：
影响因子：
2.8
通讯作者：
Jiangtao Su;Yu Liu;Jihong Liu;X. Mao;Hongqi Zhang;Hui Li;Xiaofan Wang;W. Xie
中科院分区：
文献类型：
--
作者：
Jiangtao Su;Yu Liu;Jihong Liu;X. Mao;Hongqi Zhang;Hui Li;Xiaofan Wang;W. Xie
赵和科索维切夫（天体物理学）[j] .591, 446, 2003]在一个快速旋转的太阳黑子周围，在0 - 12 Mm深度范围内发现了两个相反的亚光球涡旋流。到目前为止，还没有理论模型来解释这种流动运动。本文试图从磁通管与等离子体大尺度涡旋运动相互作用的角度来解释这一现象。在光球下较深的区域，磁力可能小于等离子体的非磁力。位于那里的涡流扭曲了磁通管，磁自由能在管内形成。在光球下方较浅的区域，磁力可能大于非磁力。因此，部分储存的磁性自由能被释放，以驱动等离子体在两个相反的方向上旋转。在0 - 3(5)和9 - 12 Mm深度范围内。此外，我们还定义了与耀斑发生有关的非势磁应力向量τ。它是根据2006年12月11日的活跃区域NOAA 10930计算的。结果表明：①在耀斑发生前和发生时，其视距应力积分在磁中性线附近依次增大，耀斑发生后减小到最小值；ii)在整个视场范围内，其横向应力的积分超过其LOS分量的积分一个数量级；iii)横向应力首先指向MNL，然后沿着它，最后远离它。我们还需要其他的数据来验证磁能是否在耀斑发生前和耀斑发生期间以水平方向向中性线传递，然后部分转化为LOS方向的能量。
Zhao and Kosovichev (Astrophys. J.591, 446, 2003) found two opposite sub-photospheric vortical flows in the depth range of 0 – 12 Mm around a fast rotating sunspot. So far there is no theoretical model explaining such flow motions. In this paper, we try to explain this phenomenon from the point of view of magnetic flux tubes interacting with large-scale vortical motions of plasma. In the deeper zone under the photosphere, the magnetic force may be less than the nonmagnetic force of plasma. The vortical flow located there twists the flux tube and magnetic free energy is built up in the tube. In the shallower zone under the photosphere, the magnetic force may be greater than the nonmagnetic force. Thus, part of the stored magnetic free energy is released to drive the plasma to rotate in two opposite directions,e.g., in the depth ranges of 0 – 3(5) and 9 – 12 Mm. In addition, we also define a vector of nonpotential magnetic stressτ, which can be related to flare occurrence. It is calculated for the active region NOAA 10930 on 11 December 2006. We find that:i) the integral of its line-of-sight (LOS) stress successively increases around the magnetic neutral line (MNL) prior to and during the flare and decreases to a minimum after the flare;ii) the integral of its transverse stress exceeds the integral of its LOS component by one order of magnitude over the whole field of view;iii) the transverse stress first points toward the MNL, then along it, and finally it points away from it. We need other data to verify whether or not the magnetic energy is transported in the horizontal direction to the neutral line, and then partly changes into the energy in LOS direction before and during the flare.