Rotationally driven magnetic reconnection in Saturn's dayside
Rotationally driven magnetic reconnection in Saturn's dayside
复制标题
土星白天的旋转驱动磁重联
DOI：
10.1038/s41550-018-0461-9
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发表时间：
2018
期刊：
影响因子：
14.1
通讯作者：
Dougherty M K
中科院分区：
文献类型：
--
作者：
Guo R L;Yao Z H;Wei Y;Ray L C;Rae I J;Arridge C S;Coates A J;Delamere P A;Sergis N;Kollmann P;Grodent D;Dunn W R;Waite J H;Burch J L;Pu Z Y;Palmaerts B;Dougherty M K
磁重联是一个关键过程，它使带电粒子爆炸性加速，产生星云耀斑、太阳耀斑和令人惊叹的极光等现象。在行星磁层中，磁重联经常在昼侧磁层顶和夜侧磁盘中被发现，那里的薄电流片条件有利于重联。由于太阳风的压缩，昼侧的磁盘通常被认为比夜侧厚，因此不是重联的理想环境。相反，最近的一项关于磁通量循环的统计研究强烈表明，磁场重联必须发生在土星的昼侧磁层。此外，高能等离子体的来源可能存在于巨型行星磁层的正午扇区。然而，到目前为止，昼侧磁重联只在磁层顶被发现。在这里，我们报告的直接证据，近中午重新连接在土星的磁盘使用测量卡西尼号航天器。测得的高能电子和离子（范围从几十到几百keV）和估计的能量通量约2.6 mW m-2的重联区域内是足够的电源极光。我们认为，昼侧磁盘重联可以解释在昼侧巨行星的磁层，这可能会促进我们的准周期性注入的相对论电子和极光脉动的理解突发现象。
Magnetic reconnection is a key process that explosively accelerates charged particles, generating phenomena such as nebular flares, solar flares and stunning aurorae. In planetary magnetospheres, magnetic reconnection has often been identified on the dayside magnetopause and in the nightside magnetodisc, where thin-current-sheet conditions are conducive to reconnection. The dayside magnetodisc is usually considered thicker than the nightside due to the compression of solar wind, and is therefore not an ideal environment for reconnection. In contrast, a recent statistical study of magnetic flux circulation strongly suggests that magnetic reconnection must occur throughout Saturn’s dayside magnetosphere. Additionally, the source of energetic plasma can be present in the noon sector of giant planetary magnetospheres. However, so far, dayside magnetic reconnection has only been identified at the magnetopause. Here, we report direct evidence of near-noon reconnection within Saturn’s magnetodisc using measurements from the Cassini spacecraft. The measured energetic electrons and ions (ranging from tens to hundreds of keV) and the estimated energy flux of ~2.6 mW m–2within the reconnection region are sufficient to power aurorae. We suggest that dayside magnetodisc reconnection can explain bursty phenomena in the dayside magnetospheres of giant planets, which can potentially advance our understanding of quasi-periodic injections of relativistic electrons and auroral pulsations.