Thèse de doctorat en Astronomie et astrophysiqueAstronomie et astrophysique
Soutenue en 2015
à Observatoire de Paris en cotutelle avec Georgia State University, Department of Physics and Astronomy , dans le cadre de École doctorale Astronomie et astrophysique d'Île-de-France (Meudon, Hauts-de-Seine1992-....) , en partenariat avec Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (Paris) (laboratoire) .
Le président du jury était Farrokh Vakili.
Pas de résumé disponible.
Jouvence of FLUOR (JouFLU) is a major overhaul of the FLUOR (Fiber Linked Unit for Optical Recombination) beam combiner built by the Laboratoire d’études spatiales et d’instrumentation en astrophysique (LESIA) and installed at the CHARA Array. These upgrades improve the precision, observing efficiency, throughput, and integration of FLUOR with the CHARA Array as well as introduce new modes of operation to this high-precision instrument for interferometry. Such high precision observations with FLUOR have provided the first unambiguous detections of hot dust around main sequence stars, showing an unexpectedly dense population of (sub)micrometer dust grains close to their sublimation temperature, 1400 K. Competing models exist to explain the persistence of this dust; some of which suggest that dust production is a punctuated and chaotic process fueled by asteroid collisions and comet infall that would show variability on timescales of a few years. By re-observing stars from the exozodiacal disks survey we have searched for variations in the detected disks. We have found evidence that for some stars the amount of circumstellar flux from these previously detected exozodiacal disks, or exozodis, has varied. The flux from some exozodis has increased, for some the flux has decreased, and for a few the amount has remained constant. These results are intriguing and will be no doubt useful for future modeling of this phenomenon. Furthermore, long-term monitoring is suggested for some of these objects to confirm detections and determine the rate of variation.