论文标题
IO的足迹尾巴中的交替发射特征：可能原因的磁性水力学模拟
Alternating emission features in Io's footprint tail: Magnetohydrodynamical simulations of possible causes
论文作者
论文摘要
IO相对于木星磁层中的等离子体的运动产生了沿磁场线传播的Alfvén波，这些波沿其路径部分反射。这些波是极光发射的根本原因，它被细分为IO足迹（IFP），即其尾部和领先地点。 Mura等人对Juno航天器的新观察。 （2018年）显示了足迹及其尾巴的令人困惑的子结构。在这些观察结果中，脚印尾巴的极点和赤道部分之间的对称性被损坏，尾部斑点交替移位。我们表明，这些亮点在尾部中的位置与在IO圆环和木星的电离层边界上反射的alfvén波一致。然后，我们研究了三种不同的机制来解释这一现象：（1）IO电离层中的霍尔效应，（2）IO木星面对面及其相对侧之间的Alfvén波的旅行时间差异，以及（3）IO大气中的不对称。为此，我们在系统的理想化几何形状中使用磁水动力学模拟。我们使用Jovian电离层附近的Poynting通量作为产生的足迹及其尾巴的形态的代理。我们发现，大厅效应是正在考虑打破对称性的最重要机制，导致“交替的AlfvénSpot Street”。旅行时间差异有助于增强这种效果。我们没有发现证据表明IO大气中的不均匀性对尾部斑点的位置或形状产生了重大贡献。
Io's movement relative to the plasma in Jupiter's magnetosphere creates Alfvén waves propagating along the magnetic field lines which are partially reflected along their path. These waves are the root cause for auroral emission, which is subdivided into the Io Footprint (IFP), its tail and leading spot. New observations of the Juno spacecraft by Mura et al. (2018) have shown puzzling substructure of the footprint and its tail. In these observations, the symmetry between the poleward and equatorward part of the footprint tail is broken and the tail spots are alternatingly displaced. We show that the location of these bright spots in the tail are consistent with Alfvén waves reflected at the boundary of the Io torus and Jupiter's ionosphere. Then, we investigate three different mechanisms to explain this phenomenon: (1) The Hall effect in Io's ionosphere, (2) travel time differences of Alfvén waves between Io's Jupiter facing and its opposing side and (3) asymmetries in Io's atmosphere. For that, we use magnetohydrodynamic simulations within an idealized geometry of the system. We use the Poynting flux near the Jovian ionosphere as a proxy for the morphology of the generated footprint and its tail. We find that the Hall effect is the most important mechanism under consideration to break the symmetry causing the "Alternating Alfvén spot street". The travel time differences contributes to enhance this effect. We find no evidence that the inhomogeneities in Io's atmosphere contribute significantly to the location or shape of the tail spots.
