The Radial Profile of Dust Grain Size in the Protoplanetary Disk of DS Tau

TL;DR

This study uses multi-band ALMA observations and radiative transfer modeling to map the radial variation of dust grain sizes in the DS Tau protoplanetary disk, revealing inside-out growth patterns and dust depletion linked to planet formation.

Contribution

It provides the first detailed radial profile of dust grain sizes in DS Tau, linking dust evolution to planet formation processes and disk substructures.

Findings

Grain sizes decrease from centimeters in the inner disk to 30 microns in the outer regions.

Dust mass depletion within the gap is sufficient for planet formation.

Discontinuity in grain size profile at the gap-ring interface depends on dust model assumptions.

Abstract

How do dust grains in protoplanetary disks overcome rapid radial drift and grow from micron size particles to planets is not well understood. The key is to search for evidence of dust accumulation and growth as a function of radius in the disk. We investigate the radial profile of grain size in the DS Tau disk by fitting multi-band ALMA observations with self-consistent radiative transfer models. The best-fit grain sizes range from centimeters in the inner disk down to 30 micron in the outer regions. Such an inside-out decreasing tendency is consistent with theories of dust evolution. Based on the best-fit model, we find that dust of 2 Jupiter masses has been depleted within the gap. By taking the gas-to-dust mass ratio into account, the lost mass is enough to form the 3.5 Jupiter mass planet inferred by literature hydrodynamic simulations. Moreover, our modeling also indicates that at the interface region between the gap and the ring, the grain size profile shows a discontinuity, with its amplitude dependent on the dust model adopted in the radiative transfer analysis. Future multi-wavelength observations at higher angular resolutions are required to better constrain the grain size and its variation in the vicinity of disk substructures.