耀斑色球压缩区的传播与谱线的不对称性

色球压缩区是耀斑大气动力学过程的一个基本特征，是产生色球谱线红不对称性的基础。本文基于压缩区从大气高层向低层传播的理论公式，在二种不同情况下，计算得到了压缩区内物质运动速度随高度和时间的变化．结果表明，色球蒸发区压力增量Δｐ为常数时压缩区之寿命比压缩区波阵面后的压力ｐ２为常数时要长得多，这就大大缓解了以往谱线不对称性的延续时间的理论值比观测值小的矛盾。形成高度不同的谱线具有不同程度的不对称性这一观测现象也同色球压缩区的传播特性相一致。

The Propagation of Chromospheric Condensations and the Asymmetry of Spectral Lines in Solar Flares

The chromospheric condensation is a basic property of the flare dynamical process and the cause of the red asymmetry of chromospheric lines.In this paper,some theoretical formula are derived about the propagation of the chromospheric condensation from upper to lower layers. Under some assumptions with generality, the evolution of the velocity field within the condensation is numerically computed.The results show that the life time of the condensation when the pressure enhancement at the evaporation region is a constant is much larger than that when the pressure just behind the condensation front is a constant. This fact greatly reduces the discrepancy that the theoretical life time of the condensation is too short compared with the line asymmetry observations. Moreover, the observed phenomenon that those lines formed at different depths have different asymmetries is also consistent with the propagation property of the chromospheric condensation.