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Hot corinos: molécules pré-biotiques autour des protoétoiles de type solaire

Abstract : One of the major goals of modern astrophysics is to understand the
formation of our Solar System. Since low-mass protostars are suns in the making, the study of these objects and their environment provides one of the best ways to investigate the Sun's formation process and to peek in the past history of our Solar System. In my thesis, I focused on the chemistry occuring in Class 0 sources (the earliest known phases in the evolutionary scenario of low-mass protostars) by studying complex organic molecules in their envelopes. Such molecules have been discovered in IRAS16293--2422, the prototype of Class 0 sources, proving the existence of hot corinos, the inner regions of the protostellar envelope where the icy grain mantles sublimate. Some of these molecules have also been observed in comets in our Solar System, raising the question of whether (and if so, how) the chemistry of Class 0 objects affects the chemical composition of the protoplanetary disk material from which comets and other planetary bodies form.
However, it is first necessary to determine whether hot corinos are ubiquitous in low-mass protostars or if IRAS16293-2422 is an exception. This was the first goal of my thesis. The approach consisted mainly in observing three Class 0 sources to search for complex organic molecules. I thereby discovered and/or confirmed three more hot corinos.
The second goal was then to constrain the size of emission of complex molecules. For this, I carried out interferometric observations of the two brightest hot corinos: this emission is compact (<150 AU) with, in one of the sources, an extended component originating from the cooler, less dense outer envelope.
The third goal consisted in confronting the possible formation pathways with the results of my observations to try and discriminate whether complex organic molecules form via gas-phase or grain-surface reactions. Although it was not possible to arrive at a definite answer, my data seem to favor the later formation route. Moreover, the comparison of hot corinos and their high-mass analogs, the hot cores (showing that complex molecules are relatively more abundant in hot corinos), also support grain-surface synthesis of these molecules.
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Contributor : Sandrine Bottinelli <>
Submitted on : Thursday, January 18, 2007 - 6:58:52 PM
Last modification on : Friday, November 6, 2020 - 4:04:07 AM
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Sandrine Bottinelli. Hot corinos: molécules pré-biotiques autour des protoétoiles de type solaire. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I; University of Hawai`i, 2006. Français. ⟨tel-00125287⟩

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