Spectro-interferometric imaging of protoplanetary disks

Star and planet formation is one of the most active and exciting research areas of modern astrophysics. Many of the fundamental open questions in this field are related to the structure and physics of the innermost regions of protoplanetary disks, where material is transported onto the forming star, ejected in powerful jets & outflows, or accreted onto newly-formed planets. However, most of the aforementioned processes take place in the inner few astronomical units around the star, eluding a direct investigation with conventional imaging techniques. In this research project, we will employ the new opportunities provided by infrared interferometry to obtain model-independent images of the terrestrial planet-forming zone of protoplanetary disks. Providing the angular resolution of a diffraction-limited 200 m optical telescope, these images will yield unique constraints on disk+accretion physics and allow us to search for planet-related disk surface structures, such as tidally cleared gaps or hot accretion spots around embedded protoplanets. Using existing and upcoming infrared & sub-mm instrumentation at the VLTI, CHARA and ALMA interferometers, we will spatially resolve the inner disk regions over a wide wavelength range. In order to derive the 3-D density & temperature distribution and dust composition, we will employ the TORUS gas+dust radiative transfer code. Employing high spectral dispersion (up to R=12000), our interferometric observations will spatially and spectrally resolve the origin of spectral line emission, providing direct information about the gas velocity field on sub-AU scales. The spectro-interferometric and spectroscopic data will be modelled using a large TORUS line radiative transfer grid, providing fundamental new constraints on the mass accretion and outflow launching mechanism in YSOs.