标题： 地球的阿尔芬之翼：揭示磁场线拓扑结构随电子分布的动力学变化 显示英文标题

标题： Earth's Alfvén Wings: Unveiling Dynamic Variations of Field-line Topologies with Electron Distributions

摘要： 2023年4月24日的日冕物质抛射（CME）磁云（MC）包含了次阿尔芬太阳风，将地球磁层从传统的弓激波磁尾结构转变为阿尔芬翼结构。利用磁层多尺度（MMS）任务的测量数据，我们首次展示了当航天器穿越这一转变过程中的各种磁场拓扑结构时的电子分布特征。具体而言，我们描述了次阿尔芬磁云内部、晨昏翼磁场线以及闭合磁场线上的电子特性。这些特征包括磁云区域内的偏流层电子和沿晨昏翼磁场线流动的高能keV电子。我们展示了双翼重联的分布特征，定义为晨昏阿尔芬翼磁场线与地磁暴际磁场（IMF）之间的重联现象。这些特征包括由部分耗尽的磁云电子和具有能量及俯仰角变化的双向高能电子组成的四个电子群体。这些分布揭示了北向IMF条件下的爆发性磁重联证据。 显示英文摘要

摘要： The magnetic cloud (MC) of the Coronal Mass Ejection on April 24, 2023, contains sub-Alfv\'{e}nic solar wind, transforming Earth's magnetosphere from conventional bow-shock magnetotail configuration to Alfv\'{e}n wings. Utilizing measurements from the Magnetosphere Multiscale (MMS) mission, we present for the first time electron distribution signatures as the spacecraft traverses through various magnetic topologies during this transformation. Specifically, we characterize electrons inside the sub-Alfv\'{e}nic MC, on the dawn-dusk wing field lines and on the closed field lines. The signatures include strahl electrons in MC regions and energetic keV electrons streaming along the dawn and dusk wing field lines. We demonstrate the distribution signatures of dual wing reconnection, defined as reconnection between dawn-dusk Alfv\'{e}n wing field lines and the IMF. These signatures include four electron populations comprised of partially-depleted MC electrons and bi-directional energetic electrons with variations in energy and pitch-angle. The distributions reveal evidence of bursty magnetic reconnection under northward IMF.