Planets born in circumstellar disks create various disk substructures, such as gaps, rings, spirals, vortices. Similar structures are observed widely with ALMA, SPHERE and similar instruments. At least some of these disk features are likely due to forming planets, however there are also other mechanisms to explain them. Planets also create various motions inside the protoplanetary disks, e.g. the meridional circulation that was recently observed with ALMA.
Carrying out high resolution, 3D dust+gas hydrodynamic simulations with radiative transfer already included, allow us to create realistic “mock observations” or “synthetic images” for a given instrument & telescope combination. These mock observations can be compared with already existing real data, or prepare for future observational proposals. We use them to understand how massive forming planets could be observed with the different instruments, how the planet-disk interactions look like on various wavelengths and what planet-generated features we can observe with the current & near-future instrumentation. Furthermore, since the 3D hydrodynamic simulations exactly inform us about the dust- and gas disk mass, we can use the mock observations to determine how much we underestimate the real disk masses due to assuming an optically thin disk.