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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2009 > Séminaires 2009 > Le jeudi 12 mars à 14h

Le jeudi 12 mars à 14h

Naoki Terada (NIICT, Tokyo)

The Kelvin-Helmholtz instability at the Mercury’s magnetopause

le jeudi 12 mars à 14h

Vélizy salle 224

Effects of ion mass-loading on the development of the Kelvin-Helmholtz
(K-H) instability at the Mercury’s magnetopause are investigated using
both linear theory and numerical simulations. Linear theory predicts
that a planetary dayside magnetopause becomes absolutely unstable
against the K-H instability, when the magnetospheric plasma adjacent
to it has a mass density about an order of magnitude greater than that
of the magnetosheath. The K-H instability evolves approximately in the
center of mass frame between two plasmas flowing in opposite
directions to each other. Because of the sunward convection of the
magnetospheric plasma on the dayside, the center of mass frame between
the magnetosphere and the magnetosheath plasmas can be in the rest
frame at some locations of the magnetopause, leading to an absolute
evolution of the K-H mode. Global multi-ion-species MHD simulations
are then invoked to examine its nonlinear evolution. For southward IMF
cases, we find that magnetic reconnection takes place both at subsolar
region and inside vortices as a result of evolution of the K-H mode in
an anti-parallel field lines condition. Simulation results for
northward IMF cases are compared with the observational findings of
the MESSENGER 1st flyby. This process may take place not only at the
Mercury’s magnetopause but also at that of Earth during the events of
drainage plume from the plasmasphere, and also at those of other
magnetized planets with extended atmosphere such as close-in
exoplanets (hot Jupiters).


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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Exploitant du site : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Pascal Chabert (Directeur)