Interaction between the turbulent solar wind and a planetary magnetosphere: a 2D comet example

Abstract

Using the newly developed code \emph{Menura}, we present the first global picture of the interaction between a turbulent solar wind and a planetary obstacle in our solar system, namely a comet. This first publication aims at shedding lights on the macroscopic effect of the upstream solar wind turbulence on the induced magnetosphere of a comet. Using a hybrid Particle In Cell simulation code, we model a medium activity comet, using both a turbulent and a laminar solar wind input, for a direct comparison between the two regimes. We show how the turbulent characteristics of the solar wind lead to a smaller obstacle size. We then present how the upstream turbulent structures, traced by the perpendicular magnetic field fluctuations absent in the laminar case, self-consistently drape and pile-up around the denser inner coma, forming intense plasmoids downstream of the nucleus, pulling away dense cometary ion bubbles. This pseudo-periodic erosion phenomenon re-channels the global cometary ion escape and as a result, the innermost coma is found to be on average 45\% less dense in the turbulent case than predicted by simulating a laminar upstream flow.