The dust content of protoplanetary disks plays a crucial role in the planet formation process. The key ingredients are not only the total budget of solid mass and the dust particle size distribution, but also how these are distributed throughout the protoplanetary disk. Characterizing the dust surface density, particle properties, and size distribution within the disk and its substructures is, therefore, critical in order to shed light on how and where in the disk planetesimals might form.
In this talk I will describe our current observational knowledge of the dust content of protoplanetary disks. I will show recent detailed studies of various protoplanetary disks that we have performed using multi-wavelength high-resolution observations taken with ALMA and VLA. One of our main results is that the emission from most of the disks’ substructures is optically thick even up to 3 mm, implying that flux-based dust mass measurements can be significantly underestimated. These high optical depths can also severely limit our ability to characterize the dust content of disks, especially in the inner tens of au where most planets are thought to be formed, including our own Solar System. I will discuss how we can circumvent these issues by observing at longer wavelengths. I will also talk about some of our recent efforts to observationally constrain other dust grain properties in disks such as the grain composition, porosity, and fragility. I will finish with a forward look at our prospects to further improve our observational understanding of dust evolution and planetesimal formation.
