Mid-infrared view of cool evolved stars with the Very Large Telescope Interferometer

Two interferometric instruments are ESO's Very Large Telescope Interferometer (VLTI) - MIDI and AMBER operating in the mid-infrared (8-13 mu m) and the near-infrared (JHK), respectively - have proven to be very powerful to study the physical properties of the circumstellar material around evolved stars. With the "spectro-interferometric" capability of MIDI and AMBER, we can disentangle spectral and spatial information on the observed object. VLTI observations have confirmed our pictures on the circumstellar environment of cool evolved stars in some cases but brought about entirely unexpected pictures in other cases. Here, we present our recent results obtained with VLTI/MIDI.