Numerical Simulations of Solar Chromospheric Jets Associated with Emerging Flux
Numerical Simulations of Solar Chromospheric Jets Associated with Emerging Flux
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DOI：
10.1093/pasj/65.3.62
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发表时间：
2013-01
影响因子：
2.3
通讯作者：
S. Takasao;H. Isobe;K. Shibata
中科院分区：
文献类型：
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作者：
S. Takasao;H. Isobe;K. Shibata
利用二维磁流体动力学（MHD）模拟研究了与出射通量有关的色球喷流加速机制。我们发现色球层和光球层的磁重联产生的慢模激波在色球层喷流的加速机制中起着关键作用。一个重要的参数是磁场重联的高度。当磁场重联发生在光球层附近时，重联流出会与等离子体β远大于1的区域发生碰撞。然后等离子体沿着磁场运动。该运动产生慢模式波。当慢波向上传播时，它发展成一个强的慢激波。当慢激波穿过过渡区时，过渡区被抬升。结果，我们得到了色球喷流作为抬升的过渡区。当色球上层发生磁场重联时，由于洛仑兹力和磁场的鞭状运动的共同作用，色球等离子体被加速。我们发现色球等离子体通过过渡区（陡峭的密度梯度）和从重联点发出的慢激波之间的相互作用被进一步加速。这是一种以前没有讨论过的MHD效应。
We studied the acceleration mechanisms of chromospheric jets associated with emerging flux using a two dimensional magnetohydrodynamic (MHD) simulation. We found that slow mode shock waves generated by magnetic reconnection in the chromosphere and the photosphere play key roles in the acceleration mechanisms of chromospheric jets. An important parameter is the height of magnetic reconnection. When magnetic reconnection takes place near the photosphere, the reconnection out- flow collides with the region where the plasma beta is much larger than unity. Then the plasma moves along a magnetic field. This motion generates a slow mode wave. The slow mode wave develops to a strong slow shock as it propagates upward. When the slow shock crosses the transition region, the transition region is lifted up. As a result, we obtain a chromospheric jet as the lifted transition region. When magnetic reconnection takes place in the upper chromosphere, the chromospheric plasma is accelerated due to the combination of the Lorentz force and the whip-like motion of magnetic field. We found that the chromospheric plasma is further accelerated through the interaction between the transition region (steep density gradient) and a slow shock emanating from the reconnection point. This is an MHD effect which has not been discussed before.