Magnetic storms in Mercury’s magnetosphere

Abstract

We present evidence of geomagnetic storms in Mercury's magnetosphere based on MESSENGER magnetic field observations made just before the probe impacted the planet. Our findings answer the question of whether geomagnetic storms can occur in other planetary magnetospheres. The interaction of the solar wind with Mercury's magnetosphere is known to involve flux transfer events in the dayside magnetosphere, plasmoids and flux ropes in the magnetotail, and substorm-like processes, all of which occur morphologically similar to Earth but with significant differences. The significantly weaker magnetic field, smaller magnetosphere, and much faster timescale of processes around Mercury, when compared with Earth, enable charged particles to escape its magnetosphere more efficiently through magnetopause shadowing and direct bombard of the surface. Our analysis of MESSENGER's data during a coronal mass ejection (CME) proves that, despite these substantial differences, a bifurcated ring current can form in Mercury's magnetosphere that initiates magnetic storms under strong solar wind driving.

Dynamics of Sputtered Neutral Sodium Atoms in the Near‐Mercury Space

“…Sun et al. (2022) noticed these heavy ions stretch from the northern polar cusp to the subsolar ring current region (Fu & Zong, 2022; J. T. Zhao et al., 2022; Zong et al., 2022). This equatorward expansion of planetary ion distribution is attributed to the frequent newly reconnected, twisted magnetic field lines and the precipitated ions accompanied within it.…”