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Etude des propriétés physiques des astéroïdes

Abstract : As the primitive, remnant building blocks of the solar system formation, asteroids offer clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Their study will allow to constrain the models of the solar system formation. We deduce the mineralogical composition of asteroids by comparing their reflectance spectra with those of terrestrial and meteoritical samples. However, space weathering processes alter the optical properties of the asteroid surfaces. This alteration modifies the color of most asteroids but bot all. Thus, it appears fundamental to understand the effect of these processes on every type of meteorite in order to investigate in more detail the physical properties of asteroids. During my thesis, I used spectroscopy in order to the physical properties of main-belt asteroids and near-earth objects. The aim of the NEO survey has been to make a taxonomy of this population in order to determine the source(s) of re-supply of this population (maib-belt, comets). I also observed the Karin family, that formed 5.8 Myr ago from the breakup of a single parent body, in order to have some hints on the internal structure and composition of the parent body (homogeneous or differentiated). Finally, I observed the targets (Lutetia and Steins) of the Rosetta mission, as well as the two candidates (Ceres and Vesta) of the Dawn mission. These data will allow to perform a comparison with the results obtained in-situ. I also performed irradiation experiments in a laboratory in order to reproduce the solar wind effects on differents samples. These experiments allowed to build a space weathering model which can be used with different scattering laws (Hapke, Shkuratov). The irradiation of an eucrite allowed to suggest the presence of a magnetic field on Vesta. This prediction can be confirmed by ground based observation and/or by the Dawn mission.
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Submitted on : Monday, March 18, 2019 - 3:42:43 PM
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  • HAL Id : tel-02071434, version 1


Pierre Vernazza. Etude des propriétés physiques des astéroïdes. Astrophysique [astro-ph]. Observatoire de Paris, 2006. Français. ⟨tel-02071434⟩



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