# Etude des Envirronements Circumstellaires en Imagerie a Haut Contraste et a Haute Resolution Angulaire

Abstract : n the context of the search for brown dwarfs and giant planets companions to stars, as well as circumstel lar disks, a first part of my work has been devoted to the study of the detection capabilities performed b y high contrast and high angular resolution instruments. I have been, mainly, interested by the instrument s, which presently equip the large ground based telescopes, and which are composed of an adaptive optics s ystem 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 co nditions. 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 t heir evolutionary status and the stars with planets, indirectly detected by the radial velocity measuremen ts.\\ I present the detection of several substellar candidates in the young, nearby associations $\beta$ Pictori s, MBM~12 and Tucana-Horologium, as well as an unprecedented work on the fraction of stellar companions an d 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 ca pabilities performed thanks to our deep imaging strategy.
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https://tel.archives-ouvertes.fr/tel-00010489
Contributor : Gael Chauvin <>
Submitted on : Friday, October 7, 2005 - 11:22:59 PM
Last modification on : Friday, September 25, 2020 - 11:16:03 AM
Long-term archiving on: : Friday, September 14, 2012 - 3:05:15 PM

### Identifiers

• HAL Id : tel-00010489, version 1

### Citation

Gael Chauvin. Etude des Envirronements Circumstellaires en Imagerie a Haut Contraste et a Haute Resolution Angulaire. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2003. Français. ⟨tel-00010489v1⟩

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