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

¹ Swedish Institute of Space Physics, Box 812, 981 28 Kiruna, Sweden
e-mail: etienne.behar@irf.se
² Lagrange, CNRS, OCA, Université Côte d’Azur, Boulevard de l’Observatoire, 06088 Nice, France
³ LPC2E, CNRS, Univ. Orléans, CNES, 45071 Orléans France

Received: 8 July 2022
Accepted: 13 January 2023

Abstract

Context. Using the newly developed code 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.

Aims. This first publication sheds light on the macroscopic effect of the upstream solar wind turbulence on the induced magnetosphere of a comet.

Methods. Using a hybrid particle-in-cell simulation code, we modelled a medium activity comet using turbulent and laminar solar wind input, for a direct comparison between the two regimes.

Results. 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; 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.