München 2019 – wissenschaftliches Programm
EP 9.8: Poster
Donnerstag, 21. März 2019, 16:30–19:00, Durchgangshalle
Paleomagnetospheric Modelling of the Hermean Magnetosphere — •Daniel Heyner — TU Braunschweig, Braunschweig, Deutschland
Mercury possesses a very weak magnetic field. The surface field strength at the equator is 190 nT which is ca. 160 times weaker than the terrestrial value. Magnetic field measurements from the MESSENGER probe indicate the possibility of a much stronger dipole moment in ancient times, allowing even a field of comparable surface field strength as the terrestrial value. Mercury is also subject to an intense inflow of solar wind plasma due to its proximity to the Sun. This flow is not steady having intrinsic natural variations as well as the variation due to the changing heliocentric distance along the Hermean orbit. It is known that the solar wind dynamic pressure is also exponentially decaying over time. The solar wind plasma flow exerts an inward pressure on the magnetopause, the outermost boundary of the magnetosphere. The internal magnetic field pressure by the planetary dipole acts against the inward solar wind push. Thus, pressure equilibrium defines the spatial scale of the magnetopause. The electric currents in the magnetopause induce a magnetic field acting on the planet, driving e.g. induction currents in the interior and maybe even quench the internal dynamo process. It is demonstrated, how the magnetopsheric spatial scale changes with a time-dependent internal dipole moment and solar wind pressure using a semi-empirical magnetospheric modeling approach. The resultant magnetopause fields acting on the planet are computed and discussed.