Étude de l'environnement proche des étoiles jeunes par interférométrie. Vers l'imagerie avec la recombinaison multiple en optique intégrée.

摘要

The close environments of Herbig AeBe stars is still a matter of debate. This stars are the massive counterparts of the T Tauri stars, and consequently, their evolution is faster. It is still unclear whether the surrounding matter located within the innermost regions can be structured in a similar way i.e. with an accretion disk, tunnel flows and bipolar jets. Only optical interferometry can probe the innermost astronomical units. My thesis aims at using and developing new diagnostics at high angular resolution to study young stellar objects, and more particularly Herbig AeBe stars. At first, I present my instrumental contribution to the development of the spectro-imager instrument VSI, which goal is to provide with images at high angular resolution that are fully independent from models. I describe the design of the integrated optics combiners that are at the heart of the instrument, its complete characterization in laboratory as well as the constraints set up by the expected performances of an imaging instrument. Secondly, I present two results that were obtained with spectro-interferometry, on a Herbig Be star (MWC297) and on a Herbig Ae star (AB Aur), observed with the AMBER/VLTI instrument in its medium spectral resolution mode, accross the Brackett Gamma line. While in MWC297, this emission could be reproduced using an expanding gas envelope, it seems to be located close to the inner rim of the dust disk in the case of ABAur. A specific analysis of both photometric and interferometric measurements using a radiative transfer code is presented. In the last part, I present a study of FU Orionis multiplicity. This analysis is based on closure phase measurements. This quantity gives access to the degree of asymetry of the emitting region, at the milliarcsecond scale. The goal of this work is to test the possible existence of a close companion, probably responsible of the luminosity eruptions observed in FU Ors.