Abstract
Based on Spitzer selected YSOs, we present a study of transition disks located in Lupus. Several mechanisms have been proposed to explain their defining characteristic: an inner opacity hole and an optically thick outer disk. These processes are: planet formation, grain growth, photoevaporation, tidal truncation in close binaries. We have carried out Adaptive Optics (AO) imaging, submillimeter photometry, and echelle spectroscopy in order to observationally characterize our transition disk sample. With the analyzed data we can distinguish the four scenarios and identify candidate transition disk systems that are currently forming planets. Such objects are excellent targets to be followed-up with Herschel and ALMA.
