This review summarizes the research of Mercury's magnetosphere in the Post-MESSENGER era and compares its dynamics to those in other planetary magnetospheres, especially to those in Earth's magnetosphere. This review starts by introducing the planet Mercury, including its interplanetary environment, magnetosphere, exosphere, and conducting core. The frequent and intense magnetic reconnection on the dayside magnetopause, which is represented by the flux transfer event "shower", is reviewed on how they depend on magnetosheath plasma beta and magnetic shear angle across the magnetopause, following by how they contribute to the flux circulation and magnetosphere-surface-exosphere coupling. In the next, the progress of Mercury's magnetosphere under extreme solar events, including the core induction and the reconnection erosion on the dayside magnetosphere, the responses of the nightside magnetosphere, are reviewed. Then, the dawn-dusk properties of the plasma sheet, including the features of the ions, the structure of the current sheet, and the dynamics of magnetic reconnection, are summarized. The last topic reviews the particle energization in Mercury's magnetosphere, which includes the energization of the Kelvin-Helmholtz waves on the magnetopause boundaries, reconnection-generated magnetic structures, and the cross-tail electric field. In each chapter, the last section discusses the open questions related with each topic, which can be considered by the simulations and the future spacecraft mission. We close by summarizing the future BepiColombo opportunities, which is a joint mission between ESA and JAXA, and is en route to Mercury.
Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations?
广义相对论利用日震学中太阳的角动量S = 190 x 10^39 kg m^2 s^-1,预测水星近日点经度的兰斯-瑟林岁差为-2.0毫角秒/世纪(在天体赤道参考系中计算)。在4-σ水平上,它与标准牛顿/爱因斯坦岁差的0.4 +/- 0.6毫角秒/世纪修正值不一致,只要后者完全归因于标架拖曳。补充岁差是最近用INPOP 10a星历表与一个长行星数据记录(1914-2010年)进行全球拟合确定的,其中包括2008-2009年从信使号航天器收集的3个数据点。INPOP 10a模型根本不包括太阳重力磁场,因此它的特征可能在数据简化过程中被部分删除。另一方面,Lense-Thirring进动可能在一定程度上被竞争进动所抵消,这些竞争进动是由太阳四极质量矩和PPN参数β进入Schwarzschild类1 PN进动的小错误建模引起的,两者都是在INPOP 10a中建模的。相反,水星本身的扁率对其近日点的影响可以忽略不计。最大的单个小行星和小行星环的错误模型行为也是如此。未来对目前正在进行的信使号任务的更多观测结果的分析将进一步阐明这一问题,如果得到证实,可能会挑战我们目前对目前公认的引力定律和/或太阳物理特性的看法。
Spectral Properties and Energy Injection in Mercury's Magnetotail Current Sheet
Boston University(波士顿大学);Laboratoire de Physique des Plasmas (LPP), CNRS, Observatoire de Paris, Sorbonne Université, Université Paris Saclay, Ecole polytechnique, Institut Polytechnique de Paris(等离子体物理实验室,法国国家科学研究中心,巴黎天文台,索邦大学,巴黎萨克雷大学,巴黎综合理工学院,巴黎理工学院);Department of Climate and Space Sciences and Engineering, University of Michigan(密歇根大学气候与空间科学与工程系);INAF-Institute for Astrophysics and Space Planetology(意大利国家天体物理学研究所空间与行星物理学研究所)
Evolution of a Long-Duration Coronal Mass Ejection and its Sheath Region Between Mercury and Earth on 2013 July 9-14
利用现场测量和遥感观测,我们研究了2013年7月9日离开太阳并撞击水星和地球的日冕物质抛射(CME),而行星处于径向对齐(在$3^\circ$内)。日冕仪测得的日冕物质抛射的初速度为580 $\pm$ 20 km s $^{-1}$,在水星的推断速度为580 $\pm$ 30 km s $^{-1}$,在地球测得的最大速度为530 km s $^{-1}$,这表明它在内日球层没有大幅减速。信使号和{ \it Wind}的磁场测量结果显示,两颗行星上都有非常相似的磁性喷出物。我们认为CME的膨胀是由喷出物持续时间和水星与地球之间的磁场强度的降低以及由{ \it Wind}测量的{ \it in situ}速度剖面测量的。长时间的磁性喷出物(在水星和地球上分别为20和42小时)被发现与1 AU处相对缓慢膨胀的喷出物有关,这表明喷出物的大尺寸是由于CME本身或其在日冕或最内层日光层中的膨胀,而不是由于0.45 AU的水星和1 AU的地球之间的快速膨胀。我们还发现的证据表明,CME鞘是由压缩的物质积累的冲击形成之前,以及最近的冲击材料。
Properties and Radial Evolution of Solar Wind Turbulence Near Mercury's Orbit
Boston University(波士顿大学);Institute for Advanced Study, Princeton(普林斯顿高等研究院);Laboratoire de Physique des Plasmas (LPP), CNRS, Observatoire de Paris, Sorbonne Université, Université Paris Saclay, Ecole polytechnique, Institut Polytechnique de Paris(等离子体物理实验室(LPP),法国国家科学研究中心,巴黎天文台,索邦大学,巴黎萨克雷大学,巴黎综合理工学院,巴黎理工学院);University of Michigan(密歇根大学)