HR: 1340h
AN: SH43A-1138    [Abstracts]
TI: Venus-Solar Wind Interaction: The Role of Upstream Parameters and the Escape of Oxygen Ions
AU: J„rvinen, R
EM: Riku.Jarvinen@fmi.fi
AF: Finnish Meteorological Institute, Space Research Division, Erik Palmenin aukio 1, Helsinki, 00560 Finland
AU: * Kallio, E
EM: Esa.Kallio@fmi.fi
AF: Finnish Meteorological Institute, Space Research Division, Erik Palmenin aukio 1, Helsinki, 00560 Finland
AU: Janhunen, P
EM: Pekka.Janhunen@fmi.fi
AF: Finnish Meteorological Institute, Space Research Division, Erik Palmenin aukio 1, Helsinki, 00560 Finland
AB: Neither Venus nor Mars has a strong global intrinsic magnetic field and therefore the solar wind can flow close to the planets in high neutral density regions. Because of the formed direct interaction between the atmosphere/exosphere and the solar wind, the ionized atmospheric constituents can be picked up by the solar wind. Charge exchange between solar wind protons and planetary neutrals, instead, produces energetic neutral hydrogen atoms (H-ENA) which are thus a manifestation of the direct interaction between the solar wind and planetary neutrals. Picked-up planetary O+ ions in turn form energetic neutral oxygen atoms (O-ENA) via a charge exchange process. The ion escape, H-ENAs, O-ENAs and electrons will be investigated at Venus and Mars by two identical instruments: ASPERA-4 on Venus Express and ASPERA-3 on Mars Express. We have developed a self-consistent, three-dimensional quasi-neutral hybrid (ions are particles, electrons a fluid) simulation to study the Venus-solar wind interaction and, in particular, the forthcoming ASPERA-4 and magnetic field measurements. In the presentation we show quasi-neutral hybrid model runs to study basic 3-D features of the Venusian plasma and magnetic field environments. We analyze (1) the role of the IMF x-component, (2) the velocity of the solar wind and (3) the role of the escaping O+ ions. Finally, implications for the forthcoming Venus Express particle and magnetic field measurements are discussed.
DE: 2459 Planetary ionospheres (5435, 5729, 6026)
DE: 2780 Solar wind interactions with unmagnetized bodies
DE: 5421 Interactions with particles and fields
DE: 5440 Magnetic fields and magnetism
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005