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Le Milieu Interstellaire Local: région test et avant-plan.

Séverine Raimond 1 
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : The three-dimensional distribution of the interstellar matter (or interstellar medium, ISM) in the Galaxy is a very general tool not yet really developed today, a major reason being the difficulty of estimating distances to complexes, what will change soon thanks to the Gaia mission. Indeed the determination of the cloud distances resorts to the absorption measurements method along lines-of-sight toward the stars, and so requires the values of their distance, which will be precisely measured by Gaia. One of the methods allowing to estimate the tree-dimensional structure of the ISM is the inversion of the absorbant columns of gas and dust measured toward a big number of stars situated at different distances and in different directions. The work presented in this thesis contributes to the constitution of the databases necessary for this method, for the nearby interstellar medium, for the study of the results of these inversions, as well as the links between different tracers of the interstellar matter. This is placed in the prospect of the advances which will be allowed in this area thanks to Gaia and the programs supporting the mission. The title of this thesis refers in this sense to the uses of the cartographies of the nearby ISM as test of the inversion tools which must be developped toward the largest scales in the context of the mission, and moreover to the uses of the maps as supports for the determination of stellar parameters, providing constraints on the reddening when it cannot be infered in an independent way by the spectroscopic observations. A first part relates the acquisition and the analysis of spectroscopic data, particularly with the correction of telluric lines and the extraction of the informations from the neutral sodium NaI and the CaII ion interstellar lines. A second part presents the whole results. A third part is dedicated to the 3D distributions obtained by inversion of the database and to the search of links between nearby dense clouds reconstructed in three dimensions and the radio emission measurements by HI and CO. A fourth part is a preliminary study of the analysis of spectroscopic surveys as a support for Gaia. A first section is the study of the uncertainties due to the saturation of the interstellar lines of neutral sodium for the distant stars and the potential methods to reduce them. A second part is dedicated to the extraction of two diffuse interstellar bands and to the study of their correlation with the other tracers, as well as the interpretations of anormal values in these diffuse bands. The first goal of these studies is the search of an evaluation of the extinction independant of the photometric measurements of Gaia, for the distant objects.
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Submitted on : Thursday, January 31, 2013 - 2:15:35 PM
Last modification on : Tuesday, November 16, 2021 - 4:04:31 AM


  • HAL Id : tel-00687722, version 2


Séverine Raimond. Le Milieu Interstellaire Local: région test et avant-plan.. Astrophysique galactique [astro-ph.GA]. Université Pierre et Marie Curie - Paris VI, 2011. Français. ⟨NNT : 2011PA066676⟩. ⟨tel-00687722v2⟩



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