The independent pulsations of Jupiter's northern and southern X-ray auroras
The independent pulsations of Jupiter's northern and southern X-ray auroras
复制标题
DOI：
10.1038/s41550-017-0262-6
复制
发表时间：
2017-11-01
期刊：
影响因子：
14.1
通讯作者：
Coates, A. J.
中科院分区：
文献类型：
--
作者：
Dunn, W. R.;Branduardi-Raymont, G.;Coates, A. J.
极光热点在宇宙中以不同的尺度被观察到，并标志着周围等离子体环境和大气之间的耦合。在我们自己的太阳系中，木星拥有这种大规模能量转移的唯一可解析的例子。木星北方的X射线极光集中在一个热点上，这个热点位于木星极光的最向极的区域，并且周期性地（2，3）或不规则地（4，4）脉动。X射线发射谱线表明，木星的北方热点是由高电荷态的氧、硫和/或碳离子产生的，能量为数十MeV（参考文献（4-6）），这些离子正在进行电荷交换。相反，观测未能在南部发现类似的特征（2，3，4，4）。在这里，我们报告存在一个持续的南方X射线热点。令人惊讶的是，这种大规模的南部极光结构的行为独立于它的北方对应。利用2016年5月至6月和2007年3月进行的XMM-牛顿和钱德拉X射线活动，我们表明木星的北方和南方斑点各自表现出不同的特征，例如不同的周期性脉动和亮度的不相关变化。这些观测结果意味着，高能量的非共轭磁层过程有时会驱动木星昼侧磁层的极区。这与目前木星产生X射线的模型形成对比（4，10）。了解木星的一对热点的行为和驱动因素对于使用X射线诊断表现出这些极光现象的广泛快速旋转天体至关重要。
Auroral hot spots are observed across the Universe at different scales' and mark the coupling between a surrounding plasma environment and an atmosphere. Within our own Solar System, Jupiter possesses the only resolvable example of this large-scale energy transfer. Jupiter's northern X-ray aurora is concentrated into a hot spot, which is located at the most poleward regions of the planet's aurora and pulses either periodically(2,3) or irregularly(4,4). X-ray emission line spectra demonstrate that Jupiter's northern hot spot is produced by high charge-state oxygen, sulfur and/or carbon ions with an energy of tens of MeV (refs (4-6)) that are undergoing charge exchange. Observations instead failed to reveal a similar feature in the south(2,3,4,4). Here, we report the existence of a persistent southern X-ray hot spot. Surprisingly, this largescale southern auroral structure behaves independently of its northern counterpart. Using XMM-Newton and Chandra X-ray campaigns, performed in May-June 2016 and March 2007, we show that Jupiter's northern and southern spots each exhibit different characteristics, such as different periodic pulsations and uncorrelated changes in brightness. These observations imply that highly energetic, non-conjugate magnetospheric processes sometimes drive the polar regions of Jupiter's day side magnetosphere. This is in contrast to current models of X-ray generation for Jupiter(4,10). Understanding the behaviour and drivers of Jupiter's pair of hot spots is critical to the use of X-rays as diagnostics of the wide range of rapidly rotating celestial bodies that exhibit these auroral phenomena.