Dynamical features and spatial structures of the plasma interaction region of 67P/Churyumov–Gerasimenko and the solar wind

Abstract

In the advent of the Rosetta arrival at the comet 67P/Churyumov–Gerasimenko, we present a global 3D hybrid simulation model of the cometary plasma interaction which resolves the innermost coma sufficiently. As Rosetta will only provide local information, global simulations are required to put these local observations into a wider global perspective. In the selected scenario close to the perihelion, the gas production of the comet is large enough to trigger a cometary bow shock and a small diamagnetic cavity around the nucleus. The simulation reveals the presence of a cometary ionopause and a recombination layer, which is in general agreement with single-fluid MHD simulations. However, we found an asymmetry in the interaction region caused by the pick-up of the cometary ions, which effects all known boundaries. In addition, we study the velocity distributions of the ions and find the presence of three distinct populations of cometary ions at the inner boundaries. The bifurcation created in the ion energy spectrum might be observable by the instruments onboard the Rosetta spacecraft.