Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

P (Space and Planetary Sciences) » P-CG Complex & General

[P-CG23] Planetary Magnetosphere, Ionosphere, and Atmosphere

Sun. May 20, 2018 10:45 AM - 12:15 PM Convention Hall A (CH-A) (2F International Conference Hall, Makuhari Messe)

convener:Kanako Seki(Graduate School of Science, University of Tokyo), Takeshi Imamura(Graduate School of Frontier Sciences, The University of Tokyo), Naoki Terada(東北大学大学院理学研究科, 共同), Hiroyuki Maezawa(Department of Physical Science Osaka Prefecture University), Chairperson:Maezawa Hiroyuki(大阪府立大学大学院理学系研究科), Seki Kanako( Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo,)

11:30 AM - 11:45 AM

[PCG23-04] Prediction of global structure of Mercury's magnetosphere

*Manabu Yagi1, Kanako Seki2, Yosuke Matsumoto3, Dominique Delcourt4, Francois Leblanc4 (1.RIKEN Advanced Institute for Computational Science, 2.Graduate School of Science, University of Tokyo, 3.Graduate School of Science, Chiba University, 4.Centre national de la recherche scientifique)

Keywords:Mercury's magnetosphere, MHD simulation

From Mariner 10 and MESSENGER observations, Mercury’s magnetosphere is thought to be a miniature of the Earth’s magnetosphere. While these two magnetospheres have several characteristics in common, some critical differences are also evident. First, there is no atmospheric layer, but only tenuous exosphere. Second, center of dipole field is shifted to northward about 485km, which is equivalent to 0.2 Mercury's radius. Kinetic effects of heavy ions will also be important in Mercury's magnetosphere, because Mercury’s magnetosphere is relatively small compared to the large Larmor radii. Trajectory tracings is one of the methods to estimate the contribution of heavy ions which originate from the exosphere, while the results of the simulation are quite sensitive to the electric and magnetic field. Hence, it is important to provide a realistic field model in the trajectory tracings. In order to construct a large scale structure, we developed a MHD simulation code, and adopted it to the global simulation of Mercury’s magnetosphere. In this study, we performed MHD simulations with various kinds of solar wind parameters to investigate the interaction between solar wind plasma and offset dipole of Mercury. IMF conditions comes from Parker Spiral which has strong Bx and By component at the Mercury's orbit, and fluctuations are added in By and Bz components. In the results of MHD simulations, global configuration of magnetosphere shows strong north-south asymmetry due to dipole offset and IMF-Bx in addition to dawn-dusk asymmetry which comes from IMF-By. IMF Bx also affects to the intensity ratio of north and south cusp pressure, while IMF By component “twist” the cusp region to longitudinal direction. Prediction of global structure of magnetosphere especially the cusp region is important not only for the understanding of magnetospheric physics itself, but also making a proposal to the observational plan of spacecraft such as Bepi-Colombo.