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Les poussières et petits corps des systèmes planétaires extrasolaires

Abstract : During my thesis, I numerically simulated the dynamical behaviour of dust and small grains around stars, applied to two ranges of stellar distance : debris disks and exozodis.Concerning debris disks, I focused on the fast moving arch-like structures observed over 15 years inside the disk of AU Mic. Supposing that they all come from a single parent body and that the dust composing the arches have the same dynamics, I showed that the parent body must be closer-in than the planetesimal belt (<25 au), on a circular orbit or static with respect to the observer. Grains must be submicronic in order to explain the apparent velocity of the arches, gained by means of stellar wind pressure. Large-scale magnetic field of the star is large enough to explain the vertical extent of the arches, but require further investigations.I also developped a numerical code in order to test the dynamical origin of dust composing exozodis, to compare its results to the observations. I showed that the classical PR-drag scenario involving grains drifting inward from a distant cold parent belt produce an excess flux in mid-infrared compared to the near-infrared, unbalanced by the pile-up. The cometary scenario, by producing dust very close to the star, emits less in mid-infrared. A ten of kilometric comets can reproduce the flux levels observed around all stars. This numerical code is also able to handle the DDE, the stellar wind pressure or the magnetic field.During my work, I showed that taking into account the dust dynamics can constrain the dust physical properties. I developped adaptative numerical tools that can handle the variety and complexity of dust observed around stars.
Keywords : Dust Simulation Disk
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Submitted on : Friday, November 8, 2019 - 6:09:23 PM
Last modification on : Thursday, November 26, 2020 - 3:31:37 PM
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  • HAL Id : tel-02356530, version 1



Elie Sezestre. Les poussières et petits corps des systèmes planétaires extrasolaires. Planétologie et astrophysique de la terre [astro-ph.EP]. Université Grenoble Alpes, 2019. Français. ⟨NNT : 2019GREAY022⟩. ⟨tel-02356530⟩



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