Effects of the surface conductivity and IMF strength on dynamics of planetary ions in Mercury’s magnetosphere - Archive ouverte HAL
Communication Dans Un Congrès Année : 2013

Effects of the surface conductivity and IMF strength on dynamics of planetary ions in Mercury’s magnetosphere

Résumé

A previous study of ion dynamics in the Mercury's magnetosphere, which uses a rescaled analytical model of the geomagnetic and electric fields for Mercury, shows that non-adiabatic motion of ions inthe magnetotail can cause a narrow band of energetic (several keV) Na+ precipitation in each hemisphere [Delcourt et al., 2003]. On the other hand, it is not evident that the magnetospheric configuration and global convection pattern in the Mercury's magnetosphere can be described with the rescaled geomagnetospheric model. In order to investigate whether the ion dynamics in the self-consistent field configuration differs from that in the rescaled model, we conducted systematic trajectory tracings of Na+ ions in the electric and magnetic fields obtained from MHD simulations of the Mercury-solar wind interaction. Comparison with a previous study, which used an analytical model by rescaling Earth's magnetosphere and assumed the existence of the distant neutral line (DNL) in Mercury's magnetotail, shows the drastic change in Na+ precipitation pattern onto due to formation of the near-Mercury neutral line (NMNL) in MHD simulations. Na+ precipitation band around 30 degrees of latitude (LAT) obtained in the previous study disappeared in the equivalent low-conductivity MHD case due to the NMNL formation, while the NMNL formation causes high-energy Na+ precipitation into equatorial region. The change in the strength of the southward IMF (sBz) alters the location ofNMNL and Na+ precipitation pattern. In the low-conductivity sBz=5 case, both the equatorial precipitation and Na+ band around LAT=30 are formed. In the high-conductivity sBz=5 case, on one hand, magnetospheric convection through polar regions is suppressed and it results in a region of dense Na+ near the planet. These results suggest that the dynamics of planetary ions in the magnetosphere of Mercury and related precipitation onto the planet surface change significantly with the activity level of Mercury'smagnetosphere. It is also suggested that we can gather information about the surface conductivity from observations of either the magnetospheric convection, distribution of Na+ ions around the planet, or precipitation pattern of Na+ ions onto the planetary surface
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Dates et versions

hal-02752250 , version 1 (03-06-2020)

Identifiants

  • HAL Id : hal-02752250 , version 1

Citer

K. Seki, N. Terada, M. Yagi, Dominique Delcourt, François Leblanc, et al.. Effects of the surface conductivity and IMF strength on dynamics of planetary ions in Mercury’s magnetosphere. International Symposium & Summer School on Planetary Science (IAPS 2013), Jul 2013, Shanghai, China. ⟨hal-02752250⟩
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