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Abstract

This Thesis is dedicated to the characterization of protoplanetary disks – the cradles of planets – and to the search for forming planets embedded in these disks. To this goal, the presented work analyses high-angular resolution observations in the near-infrared and sub-millimeter wavelength regime using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) and the Atacama Large Millimeter Array (ALMA).

SPHERE observations of the circumstellar disk around PDS 70 reveal the presence of a planetary-mass companion in the gap of the disk. This discovery is the first unambiguous detection of a planet still caught at formation within its natal disk and thus represents an unique laboratory to observationally study processes of planet-disk interactions. We perform a thorough analysis of the system using follow-up observations with ALMA, which reveals the disk to be highly structured in both dust and gas. Most prominently, gas and dust are strongly depleted around the location of PDS 70 b, in agreement with the predictions from theoretical models of planet-disk interactions. Further, analysis of the gas kinematics shows perturbations in the disk which can account for the large cavity in the dust disk.

Finally, we present an analysis of SPHERE scattered light observations of the circumbinary disk around GG Tau A. An outer dust ring and the immediate circumbinary environment shows various substructures. These are found to be the result of binary-disk interactions by comparison to hydrodynamical simulations. We conclude that the observed cavity size can be explained by the interactions with the central binary on an orbit which is coplanar with the outer disk. This system illustrates that in certain configurations, multiple systems are able to sustain massive, gas-rich disks over several million years, providing potentially favourable conditions for planet formation.