太阳低层大气中的磁重联

Magnetic reconnection in the solar lower atmosphere

本文探讨了太阳低层大气中电离效应和辐射致冷对Sweet-Parker磁重联的作用。我们发现与绝热情况相比,中性原子的电离很大程度上抑制了温度的增加。辐射致冷仅在色球上层起作用。较小的温度增量对应于重联区较大的入流速度,这可以部分解决绝热情况下入流速度同观测相比小很多的问题。我们将重联模型应用于埃勒曼炸弹和II类白光耀斑的解释,推导出了两类现象在低层大气发生时所需的物理参数。

We investigate the effect of ionization and radiative cooling on the Sweet-Parker type magnetic reconnection in the solar lower atmosphere.We find that the temperature increase can be suppressed appreciably by the ionization of neutral atoms,as compared with the adiabatic case.The effect of radiative cooling is only important in the upper chromosphere and above.A less temperature increase corresponds to a bigger inflow velocity in the reconnection region,which can partly resolve the problem that the inflow velocity in the adiabatic case is much smaller than the observed value.We apply the model to the explanation of Ellerman bombs and type Ⅱ white-light flares.We derive the required parameters that correspond to these two phenomena if they are from in situ reconnection in the lower atmosphere.