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Evolution des poussières dans les chocs

Abstract : Dust grains play a ma jor role in the evolution of the interstellar medium and galaxies. From models we know that dust is strongly destroyed in interstellar shocks powered by supernovæ explosions, so dust needs to be (re)formed in the interstellar medium. In this report, we focus on the modelling of dust processing in MHD shock waves propagating through dense clouds. This is a first step toward a more general study of the evolution of dust in the cold phase of the interstellar medium. We determine the rate of destruction of silicate and carbon dust by vaporisation and sputtering in transverse MHD shock waves, wether monofluid (J shocks) or multifluid (C shocks) with velocity below 50 km/s. Dust grains are modelled by refractory, spherical, homogeneous and non porous cores covered by an icy mantle. The dust size distribution resulting from the competition between shattering and coagulation of grains in the shock is calculated and coupled to the integration of the shock structure. We integrate the out of equilibrium charge distribution of grains, their dynamics through the shock (including their inertia and the effect of charge fluctuations), and their processing simultaneously with the calculation of the chemistry, ionisation state and the gas dynamics. This full coupling of shock structure with dust, necessary for C shocks, allows us to assess the feedback of dust processing on the dynamics of shocks. We present the first study of dust processing in J shocks in dense clouds. Some preliminary results are presented on the processing of dust in C shocks. We emphasize the particular role dust play in C shocks, very much like in dusty plasmas.
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Contributor : Vincent Guillet Connect in order to contact the contributor
Submitted on : Monday, April 6, 2009 - 4:53:14 PM
Last modification on : Thursday, October 21, 2021 - 5:10:52 AM
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  • HAL Id : tel-00332738, version 2



Vincent Guillet. Evolution des poussières dans les chocs. Astrophysique [astro-ph]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00332738v2⟩



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