ALMA Observations of Disk Substructure in 3mm Dust Continuum

Rings and gaps in protoplanetary disks are important signatures of the presence of planets. As planets orbit the host star, they carve gaps in the disk, which appear as regions with depleted emission in dust continuum images. Rings form when the presence of local pressure maxima following the gap results in a pressure gradient inversion, and the outward pressure gradient prevents dust from drifting radially inward. The ring of increased dust surface density that results is called a dust trap. Identifying a gap-ring pair as a true dust trap can verify the presence of a planet in the gap. This can be done by identifying a drop in the spectral index in the region of the ring, which is a sign of possible grain growth. Multiwavelength continuum observations of protoplanetary disks are critical to constraining such dust properties. We present preliminary results of an ALMA 3mm follow-up campaign of the 1.3 mm Disk Substructures at High Angular Resolution Project (DSHARP) dust continuum observations of young protoplanetary disks. The project targets objects from the DSHARP sample which exhibit clear ring/gap substructure. We employ a novel visibility fitting technique, frank, to model both wavelengths at high resolution. The direct fitting allows us to construct radial intensity profiles of the symmetric substructure at resolutions below that of the reconstructed beams. From these radial intensity profiles, we compute spectral index profiles, and constrain the solid disk mass and the radial distribution of maximum dust grain sizes. We also report the possibility of dust trapping in the observed rings of this sample and compare our results with literature constraints on companion parameters.