Ellerman Bombs and Jets Associated with Resistive Flux Emergence
Ellerman Bombs and Jets Associated with Resistive Flux Emergence
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DOI：
10.1086/512969
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发表时间：
2007-02
期刊：
影响因子：
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通讯作者：
H. Isobe;D. Tripathi;V. Archontis
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文献类型：
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作者：
H. Isobe;D. Tripathi;V. Archontis
利用二维磁流体动力学模拟研究了太阳磁通量涌现动力学中电阻过程的影响及其与Ellerman弹和其他动力学现象的关系。广泛接受的通量出现的情景是由于帕克不稳定性而形成和扩展Ω-shaped环。由于帕克不稳定性在有限波长λp ~ 10H-20H处增长速度最大，其中H为尺度高度（在太阳光球中≈200 km），因此如果初始通量片足够长，可能会从初始通量片上升出许多磁环。数值模拟显示了这一过程。多个新出现的环路在大气中扩展并相互作用，导致磁重联。首先，重联发生在低层大气中，这使得通量片的下沉部分出现在光球之上。这种重新连接也会引起局部加热，这可能是埃勒曼炸弹的原因。在后期，膨胀环之间的重联发生在大气高层，并产生高温重联射流，最终形成一个大的（λp）日冕环。与α激波相似的冷等离子体和致密等离子体结构也会形成。这不是由于磁重联，而是由于在膨胀环之间的等离子体的压缩。
Using two-dimensional (2D) magnetohydrodynamic simulations we study the effects of resistive processes in the dynamics of magnetic flux emergence and its relation to Ellerman bombs and other dynamic phenomena in the Sun. The widely accepted scenario of flux emergence is the formation and expansion of Ω-shaped loops due to the Parker instability. Since the Parker instability has the largest growth rate at finite wavelength λp ~ 10H-20H, where H is the scale height (≈200 km in the solar photosphere), a number of magnetic loops may rise from the initial flux sheet if it is sufficiently long. This process is shown in our numerical simulations. The multiple emerging loops expand in the atmosphere and interact with each other, leading to magnetic reconnection. At first reconnection occurs in the lower atmosphere, which allows the sinking part of the flux sheet to emerge above the photosphere. This reconnection also causes local heating that may account for Ellerman bombs. In the later stage, reconnection between the expanding loops occurs at higher levels of the atmosphere and creates high-temperature reconnection jets, and eventually a large (≫λp) coronal loop is formed. Cool and dense plasma structures, which are similar to Hα surges, are also formed. This is not because of magnetic reconnection but due to the compression of the plasma in between the expanding loops.