The Fate of Sub-Micron Circumplanetary Dust Grains I: Aligned Dipolar Magnetic Fields

TL;DR

This paper investigates the stability of charged sub-micron dust grains orbiting planets with aligned dipolar magnetic fields, analyzing how electromagnetic forces influence their trajectories and potential for escape or collision.

Contribution

It provides a comprehensive numerical and analytical study of dust grain stability across various planetary magnetic fields, extending understanding of dust dynamics in planetary environments.

Findings

Mapped regions of stability and instability for dust grains around planets.

Derived analytical boundaries for stable and unstable trajectories.

Applied models to Jupiter, Saturn, and Earth to illustrate effects.

Abstract

We study the stability of charged dust grains orbiting a planet and subject to gravity and the electromagnetic force. Our numerical models cover a broad range of launch distances from the planetary surface to beyond synchronous orbit, and the full range of charge-to-mass ratios from ions to rocks. Treating the spinning planetary magnetic field as an aligned dipole, we map regions of radial and vertical instability where dust grains are driven to escape or crash into the planet. We derive the boundaries between stable and unstable trajectories analytically, and apply our models to Jupiter, Saturn and the Earth, whose magnetic fields are reasonably well represented by aligned dipoles.