HR: 11:20h
AN: GP42A-05    [Abstracts]
TI: Simulation of MESSENGER flybys using plausible numerical dynamo models of Mercury's liquid core
AU: * Heimpel, M
EM: mheimpel@phys.ualberta.ca
AF: University of Alberta, Department of Physics, Edmonton, AB T6G-2J1 Canada
AU: Kabin, K
EM: kabin@phys.ualberta.ca
AF: University of Alberta, Department of Physics, Edmonton, AB T6G-2J1 Canada
AU: Gomez Perez, N
EM: ngomez@phys.ualberta.ca
AF: University of Alberta, Department of Physics, Edmonton, AB T6G-2J1 Canada
AU: Aurnou, J
EM: jona@ess.ucla.edu
AF: UCLA, Department of Earth and Space Sciences, Los Angeles, CA 90095-1567 United States
AB: Mariner 10 flybys of Mercury revealed a surprisingly active magnetosphere, with a bow shock and magnetopause. Although Mercury's magnetic field has an intensity of less than one-hundredth that of the Earth, it is nevertheless too strong to be explained by solar wind induction and must have an internal source. It is likely that this source is self-sustained dynamo action driven by thermo-compositional convection in a liquid outer core, the existence of which has been confirmed by recent observations of Mercury's libration. While the ratio of solid and fluid is not known, it is commonly assumed that the core is mostly solidified. This implies that the dynamo source region is a thin spherical shell. However, recent compositional models have shown that the core solidification rate is a strong function of the abundance of a light element (such as sulfur), relative to iron in the core, which suggests the possibility that Mercury has a relatively small inner core, so that a thick shell dynamo could be applicable. In March 2011 NASA's MESSENGER spacecraft is to arrive in orbit about Mercury. Due to the spacecraft's highly elliptical orbit, high resolution vector magnetic field measurements will be collected primarily in the northern hemisphere, where the periapsis is near 200 km altitude. In order to simulate Mercury's space environment we use a global MHD model that takes into account the solar wind and interplanetary magnetic field in the presence of numerically modeled dynamo source fields, which are calculated in thick and thin three-dimensional spherical shells. This approach allows us to simulate the variations of the total magnetic field in terms of the different field contributions along MESSENGER's trajectory. By constructing local and global magnetic field models from the simulated MESSENGER data we can attempt to identify features that distinguish differing models of Mercury's dynamo and internal structure.
DE: 1510 Dynamo: theories and simulations
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 5430 Interiors (8147)
DE: 5440 Magnetic fields and magnetism
DE: 6235 Mercury
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005