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La formation planétaire vue par Spitzer et le VLTI

Abstract : This thesis is divided in two main parts, oriented toward planet formation inside circumstellar disks around young solar analogs. First, I will present results obtained using Spitzer/IRS mid-infrared spectroscopic data. These spectra (5-35µm) display a large number of emission features, attributed to silicate dust grains, either in their amorphous or crystalline form. Based on large sample, I led two complementary statistical studies concerning the dust grains mineralogy. First, I show that crystalline grains are widespread inside circumstellar disks, and I show a so-called "crystallinity paradox" concerning the radial distribution of crystals, less crystals being detected in the inner regions (place of preferred formation) compared to outer regions. Amorphization processes can be responsible for these differences. Second, I also show a flattening of grain size distributions, taking place inside circumstellar disks (which was usually interpreted as grain growth). One explanation could be a change in the equilibrium between coagulation and fragmentation. In the second part of this thesis, I present results of pioneering interferometric observations, with the AMBER instrument, for two TTauri stars. These observations enable us to confirm, and refine, two existing models: i) the presence of a gap inside a transitional disk, with an inner disk close to the star, ii) the importance of scattered light when interpreting interferometric data. These works help us better understanding and constraining planet-forming regions.
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Contributor : Johan Olofsson <>
Submitted on : Monday, November 8, 2010 - 7:00:52 PM
Last modification on : Friday, November 6, 2020 - 4:11:22 AM
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  • HAL Id : tel-00534116, version 1




Johan Olofsson. La formation planétaire vue par Spitzer et le VLTI. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2009. Français. ⟨tel-00534116⟩



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