Etude des Environnements Circumstellaires en Imagerie à Haut Contraste et à Haute Résolution Angulaire

Abstract : In the context of the search for brown dwarfs and giant planets companions to stars, as well as circumstellar disks, a first part of my work has been devoted to the study of the detection capabilities performed by high contrast and high angular resolution instruments. I have been, mainly, interested by the instruments, which presently equip the large ground based telescopes, and which are composed of an adaptive optics system and an infrared camera, coupled with a stellar coronagraph. I have been particularly involved into the integration and test phases of the Nasmyth Adaptive Optics Syst em NAOS, presently installed at the UT4 telescope of the ESO Very Large Telescope, in Chili. I also develo ped a model to study and to predict the detection capabilities performed by such instruments as a function of the detector modes, the instrument characteristics, the observing configurations or the atmospheric conditions. Thinking of the limitations and the optimization of the observing detection performances has been crucial for the second part of my work, dedicated to the search for low mass companions to stars and circumstellar disks. Two types of targets have been found ideal for this study: the young, nearby associations due to their evolutionary status and the stars with planets, indirectly detected by the radial velocity measurements. I present the detection of several substellar candidates in the young, nearby associations Beta Pictoris, MBM12 and Tucana-Horologium, as well as an unprecedented work on the fraction of stellar companions and of brown dwarf companions among these stars. I also describe the recent results concerning the discovery of faint companions in the circumstellar environment of stars with planets and I present the detection capabilities performed thanks to our deep imaging strategy
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Astrophysics. Université Joseph-Fourier - Grenoble I, 2003. French


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Contributor : Gael Chauvin <>
Submitted on : Monday, October 10, 2005 - 9:58:32 AM
Last modification on : Thursday, March 10, 2011 - 10:14:49 AM

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Gael Chauvin. Etude des Environnements Circumstellaires en Imagerie à Haut Contraste et à Haute Résolution Angulaire. Astrophysics. Université Joseph-Fourier - Grenoble I, 2003. French. <tel-00010489v2>

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