Impact of subsurface convective flows on the formation of sunspot magnetic field and energy build-up
Impact of subsurface convective flows on the formation of sunspot magnetic field and energy build-up
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DOI：
10.1093/mnras/stac2635
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发表时间：
2022-10-19
影响因子：
4.8
通讯作者：
Kusano, Kanya
中科院分区：
文献类型：
--
作者：
Kaneko, Takafumi;Hotta, Hideyuki;Kusano, Kanya
强烈的太阳耀斑发生在三角点上，其特征是在一个半影中具有相反极性的磁通量。从对流区到光球的通量形成太阳黑子受到对流湍流的强烈影响。目前还没有证据表明对流流对三角点的形成有多么重要。本研究的目的是揭示对流区对流流对太阳黑子磁场形成和演化的影响。利用辐射磁流体力学代码r2d2模拟对流区磁通管的出现和输运。通过在对流区的不同位置分配扭曲磁通管，进行了93次模拟。结果表明，δ型和β型磁分布只能通过磁通管周围对流流动的差异来重现。三角斑是由光球上的正、负磁通量碰撞形成的。三角斑的单极和双极旋转是由磁扭扭驱动的，将磁螺旋度从对流区传递到日冕。我们发现光球中非势磁场的分布与对流区下流羽流的位置有很强的相关性。这种相关性可以在通量出现前20-30 h检测到。结果表明，通过探测对流区的下流剖面，可以在光球磁通量出现之前预测光球中的高自由能区。
Strong solar flares occur in delta-spots characterized by the opposite-polarity magnetic fluxes in a single penumbra. Sunspot formation via flux emergence from the convection zone to the photosphere can be strongly affected by convective turbulent flows. It has not yet been shown how crucial convective flows are for the formation of delta-spots. The aim of this study is to reveal the impact of convective flows in the convection zone on the formation and evolution of sunspot magnetic fields. We simulated the emergence and transport of magnetic flux tubes in the convection zone using radiative magnetohydrodynamics code r2d2. We carried out 93 simulations by allocating the twisted flux tubes to different positions in the convection zone. As a result, both delta-type and beta-type magnetic distributions were reproduced only by the differences in the convective flows surrounding the flux tubes. The delta-spots were formed by the collision of positive and negative magnetic fluxes on the photosphere. The unipolar and bipolar rotations of the delta-spots were driven by magnetic twist and writhe, transporting magnetic helicity from the convection zone to the corona. We detected a strong correlation between the distribution of the non-potential magnetic field in the photosphere and the position of the downflow plume in the convection zone. The correlation could be detected 20-30 h before the flux emergence. The results suggest that high free energy regions in the photosphere can be predicted even before the magnetic flux appears in the photosphere by detecting the downflow profile in the convection zone.