Infrared Spectro-Interferometry of Cool Evolved Stars

Recent years have seen a major contribution of infrared interferometry to studies on the circumstellar environment of cool evolved stars. Particularly, two interferometric instruments at ESO's Very Large Telescope Interferometer (VLTI) – AMBER and MIDI – offer the community a novel opportunity to carry out high-angular resolution observations. In the mid-infrared, where thermal emission from the circumstellar gas and/or dust is remarkable, MIDI has proven to be a powerful tool to derive the physical properties of the molecule and dust formation zone close to the star, particularly when combined with radiative transfer modeling. AMBER is also expected to shed more light on the circumstellar material closer to the star and the photosphere itself. In this paper, we present recent results on cool evolved stars obtained with VLTI as well as future prospects for interferometric observations and radiative transfer modeling for cool evolved stars.