无力场的触发重联和太阳耀斑

TRIGGERED MAGNETIC RECONNECTION OF FORCE-FREE FIELDS AND SOLAR FLARES

采用多步隐格式,对在瞬间形成的电流片的触发下的高剪切无力场的磁重联过程进行了数值模拟。磁重联首先在交界面处的非中性电流片区出现,然后向无力场区蔓延。在磁重联过程中,在无力场区形成一高温环状结构,物质向光球层流动。在高温环内侧的新喷发场区,物质向上流动。磁重联主要集中在初始电流片外侧的高剪切无力场区,高温环顶部的温度最高,位置基本固定。在磁重联的过程中,剪切磁场分量的空间梯度减小,无力场因子下降。

This paper made a numerical simulation of magnetic reconnection of highly stressed force-free field triggered by an instantaneously forned current sheet,using the multistep implicit scheme.Magnetic reconnection takes place in the non-neutral current sheet between the two fields at first,and then extends toward the for ce-free field region.During the magnetic re-connection,a hightemperature loop structure forms in the force-free field.The mass in the loop flows to the photosphere whereas the mass in the newly emerging field region on the inner side of the loop moves upward.This result agrees with the observation that solar flares occur in the red shift side of the inversion line of H chromospheric Dopplergiram.Magnetic reconnection concentrates mainly in the highly stressed force-free field region on the exterior side of the car-rent sheet.The loop has a higher temperature at its apex and keeps nearly stationary.As the magnetic reconnection proceeds,the gradient of sheared magnetic field component decreases and force-free field factor becomes smaller.The results of this paper may be applied to elucidate single-loop flares.