Plasma streams in the Hermean dayside magnetosphere: solar wind injection through the reconnection region

TL;DR

This study uses MHD simulations to analyze how solar wind interacts with Mercury's magnetic field, revealing plasma streams from reconnection regions that impact the planet's surface and magnetic environment.

Contribution

It introduces a detailed simulation of Mercury's magnetosphere with realistic solar wind parameters, highlighting plasma injection through reconnection regions.

Findings

Plasma streams originate at the reconnection region.

Precipitation of plasma along open magnetic field lines.

Magnetic field flattening observed by MESSENGER.

Abstract

The aim of this research is to simulate the interaction of the solar wind with the magnetic field of Mercury and to study the particle fluxes between the magnetosheath and the planet surface. We simulate the magnetosphere structure using the open source MHD code PLUTO in spherical geometry with a multipolar expansion of the Hermean magnetic field (Anderson, B. J. et al, 2012). We perform two simulations with realistic solar wind parameters to study the properties of a plasma stream originated in the reconnection region between the interplanetary and the Hermean magnetic field. The plasma precipitates along the open magnetic field lines to the planet surface showing a fast expansion, rarefaction and cooling. The plasma stream is correlated with a flattening of the magnetic field observed by MESSENGER due to the adjacency of the reconnection region where the solar wind is injected to the inner magnetosphere.