MHD Simulations of the Hermean Magnetosphere
Simulation of the interaction of the solar wind with the Hermean magnetosphere using the AMRVAC-MHD code.
The solar wind plasma and the plasma in planetary magnetospheres is a collisionless plasma. Under such circumstances the use of magnetohydrodynamic equations, which are based on the assumption of strong collisionality, may be questionable and kinetic simulations should be used instead. However, when the scales of interest are much larger than the ions typical
Larmor radius, MHD simulations may provide a good first order description of the three dimensional magnetosphere. MHD simulations have the advantage to be much less time and memory consuming than kinetic simulations.
The movie shows a typical simulation of the Hermean magnetosphere. The colour scale indicates density. Red lines show magnetic field lines and green lines the fluid stream lines. The bow shock formed by the supersonic solar wind encountering the Hermean obstacle is clearly visible as a density enhancement in front of the planet. The sonic Mach number of the wind is M=5.5 and the ratio of the thermal pressure to magnetic pressure in the solar wind is 0.5. The simulation is based on the
AMRVAC code.