S E M I N A R IDepartament d'Astronomia i Astrofísica
Universitat de València
Resolving the atmospheres of AGBs with IR-interferometry
Max Planck Institut für Radioastronomie, Bonn, Germany
Seminari del departament d'Astronomia i AstrofÃsica
Dijous 09 setembre 2010
Most of the stardust in the interstellar medium (ISM) comes from the dense stellar winds of Assymptotic Giant Branch (AGB) stars. The mechanism of this wind is not well understood yet. I will shortly discuss on the existing models of AGB atmospheres and winds and the problems of these models to explain the current spectroscopic and interferometric (high spatial-resolution) observations. I will finally report on new observations of a semi-regular AGB in the near-IR with the AMBER detector at the Very Large Telescope Interferometer (VLTI). A short technical description of this detector and the calibration/reduction procedure will be presented. Our observations cannot be explained with the current stellar models unless we use a mass much lower than predicted by stellar evolution and/or assume an ad-hoc warm molecular outer envelope. This would be the first spectro-interferometric evidence of an extended molecular layer around a semi-regular AGB star, and would be placed somewhere between the warm photosphere and the base of the dust-driven stellar wind.