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Nano-poussières carbonées dans les disques protoplanétaires

Abstract : This thesis focuses on spectroscopic signatures of carbon nanoparticles in the near and mid-infrared in protoplanetary disks. These signatures are widely observed in the interstellar medium and galaxies and thus represent an essential tool for studying their physical conditions. In particular, their study in the circumstellar environments of Herbig stars contributes to our knowledge of the formation of planetary systems and the dust cycle in the MilkyWay. Even if dust represents only a small percentage of galactic matter, it is key to the formation of complex chemical species, photoelectric gas heating, energy balance or structural dynamics. Thus, it participates directly in the evolution of protoplanetary disks.This work is based in particular on spatially resolved spectroscopic observation data obtained with the NaCo instrument at the VLT in the near infrared between 3 and 4 μm. The THEMIS model provides an interpretative framework for observations by proposing a physical dust model in which optical properties are calculated by considering the composition, structure and size of grain populations. THEMIS proposes a scenario of its evolution through the different phasesof the interstellar medium.The results obtained show that carbon sub-nanoparticles with high aromaticity are present in a widespread and structured manner at the surface ofprotoplanetary disks. Their degree of aromaticity increases with the intensity of the stellar radiation field. Moreover, the observation of these particles close to the star suggests their continuous replenishment. Modelling the dust emission under disk conditions highlights the contributions of dust populations according to the wavelength and the radiation field.This work is related to the preparation of the James Webb Space Telescope mission which will allow to observe protoplanetary disks over a wide infrared range (0.6-28 μm) with a resolution of 0.1”. This work also led to the production of two articles, one published and the other submitted to the journal Astronomy & Astrophysics.
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Submitted on : Friday, November 8, 2019 - 4:38:03 PM
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  • HAL Id : tel-02356309, version 1

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Thomas Boutéraon. Nano-poussières carbonées dans les disques protoplanétaires. Astrophysique galactique [astro-ph.GA]. Université Paris-Saclay, 2019. Français. ⟨NNT : 2019SACLS250⟩. ⟨tel-02356309⟩

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