Simulations de l’interaction du vent solaire avec des magnétosphères planétaires : de Mercure à Uranus, le rôle de la rotation planétaire

Abstract : The topic of the thesis is the role of planetary rotation in the global structure of the solar wind interaction with planetary magnetospheres using MHD simulations. In the Solar System, planetary magnetospheres present a wide diversity due to the various configurations of their planetary magnetic and spin axis. We discuss the distinction between slow and fast rotators from a MHD point of view. In the case of a non-rotating magnetosphere (as is the one of Mercury), we use simulations to identify the respective role of the solar wind parameters in the global structure of the plasma flow and magnetic field. In support of the BepiColombo mission, we also run simulations for two different planetary field models. The role of standing MHD modes is studied, along with a method to identify them in simulations. A fast-rotating but stationary magnetosphere, with the planetary magnetic and spin axis aligned (an example of this confiuration is Saturn) is presented in details. We worked on the influence of IMF (Interplanetary Magnetic Field) orientation and planetary angular velocity on the global structure of the magnetosphere. Finally, a random configuration, with a large angle between the planetary spin and magnetic axis, is analyzed for the first time in presence of a magnetized solar wind, using configurations inspired from the planet Uranus at solstice and equinox. In the solstice configuration, i.e. when the spin axis points to the Sun, a structure of alfvenic nature forms a helix in the magnetotail and reconnection sites between the IMF and the planetary field also form a double helix and slow down the magnetic structure. At equinox, when the pin axis is perpendicular to the Sun-Uranus direction, the helix structures disappear.
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Léa Griton. Simulations de l’interaction du vent solaire avec des magnétosphères planétaires : de Mercure à Uranus, le rôle de la rotation planétaire. Planétologie et astrophysique de la terre [astro-ph.EP]. Université de recherche Paris Sciences et Lettres, 2018. Français. ⟨tel-01906490⟩

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