Etude des processus physiques qui gouvernent l'évolution des petits corps glacés du système solaire

Abstract : Among the icy bodies of the solar system, we find the transneptunian objects (TNO) and centaurs. Centaurs orbit between Jupiter and Saturn while TNOS orbit, most of the time, beyond Neptune. These objects are mainly composed of ices but their chemical properties are not well known. I performed observations devoted to the investigation of these objects surfaces, using photometry and spectroscopy. Both of these dynamical populations are composed of objects that show different spectra in visible and near infrared wavelengths. Visible slopes can be very steep, suggesting the presence of organic compounds. The existence of such material imply irradiation processes. I analyzed spectra using several radiative transfer theories and laboratory data. Many absorption bands indicate the presence of water ice and even methane ice on the biggest ones. The biggest objects seem to have more ice on their surface than the smallest ones. So, mechanisms that govern the evolution of the object surfaces have different efficiency depending on the object size. (Cryo-volcanism, non-disruptive collision) or on the heliocentric distances (cometary activity). I determined the ices physical state of different ices like water ice and methane, pure diluted in nitrogen. These species, highly volatile, are only observed on the large objects, where gravity is big enough to retain them. I finally constrain the surface temperature of two objects from spectral thermometers. The work carried out during my thesis strongly contributed to a better understanding of these objects, introducing new constraints on their surface properties and on the probable physical processes that modified them.
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Frédéric Merlin. Etude des processus physiques qui gouvernent l'évolution des petits corps glacés du système solaire. Astrophysique [astro-ph]. Observatoire de Paris, 2007. Français. ⟨tel-02071424⟩

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