The Effects of Oscillations and Collisions of Emerging Bipolar Regions on the Triggering of Solar Flares
The Effects of Oscillations and Collisions of Emerging Bipolar Regions on the Triggering of Solar Flares
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DOI：
10.3847/1538-4357/aba61a
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
C. Boocock;K. Kusano;D. Tsiklauri
中科院分区：
文献类型：
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作者：
C. Boocock;K. Kusano;D. Tsiklauri
提前预测太阳耀斑发生的能力对人类很重要，因为它们可能对地球的环境和基础设施造成破坏。在Kusano等人的研究中，一个小尺度的双极区（BR），其通量相对于上覆场的电势分量反向，出现在极性反转线（PIL）附近，足以有效地触发太阳耀斑。在这项研究中，我们进行了进一步的三维磁流体动力学模拟研究的效果，这些小规模的BR的运动对耀斑触发的有效性。模拟了两个小尺度BRs碰撞的影响。结果表明，触发耀斑的强度取决于有多少覆盖场被BR破坏。BR的线性振荡的模拟表明，振荡沿着PIL增加耀斑强度，而振荡整个PIL减损耀斑强度。耀斑强度受较大振幅振荡的影响较大，但对振荡频率相对不敏感。在最极端的情况下，耀斑的峰值动能比非振荡BR增加了三倍以上。BR的扭转振荡的模拟表明，对耀斑强度的影响非常小。最后，碰撞BR的模拟表明，产生更强的耀斑作为耀斑触发每个单独的BR合并。这些结果表明，BR沿着剪切场的PIL运动或在同一区域内存在多个BR，都可能导致明显更强的耀斑。
The ability to predict the occurrence of solar flares in advance is important to humankind due to the potential damage they can cause to Earth’s environment and infrastructure. It has been shown in Kusano et al. that a small-scale bipolar region (BR), with its flux reversed relative to the potential component of the overlying field, appearing near the polarity inversion line (PIL) is sufficient to effectively trigger a solar flare. In this study we perform further 3D magnetohydrodynamic simulations to study the effect that the motion of these small-scale BRs has on the effectiveness of flare triggering. The effect of two small-scale BRs colliding is also simulated. The results indicate that the strength of the triggered flare is dependent on how much of the overlying field is disrupted by the BR. Simulations of linear oscillations of the BR showed that oscillations along the PIL increase the flare strength while oscillations across the PIL detract from the flare strength. The flare strength is affected more by larger amplitude oscillations but is relatively insensitive to the frequency of oscillations. In the most extreme case the peak kinetic energy of the flare increased more than threefold compared to a non-oscillating BR. Simulations of torsional oscillations of the BR showed a very small effect on the flare strength. Finally, simulations of colliding BRs showed the generation of much stronger flares as the flares triggered by each individual BR coalesce. These results show that significantly stronger flares can result from motion of the BR along the PIL of a sheared field or from the presence of multiple BRs in the same region.