Dust pileup at the dead-zone inner edge and implications for the disk shadow.
UEDA T., FLOCK M. and OKUZUMI S.
Abstract (from CDS):
We perform simulations of the dust and gas disk evolution to investigate the observational features of a dust pileup at the dead-zone inner edge. We show that the total mass of accumulated dust particles is sensitive to the turbulence strength in the dead zone, αdead, because of the combined effect of turbulence-induced particle fragmentation (which suppresses particle radial drift) and turbulent diffusion. For a typical critical fragmentation velocity of silicate dust particles of 1 m s–1, the stress-to-pressure ratio αdead needs to be lower than 3 x 10–4 for dust trapping to operate. The obtained dust distribution is postprocessed using the radiative transfer code RADMC-3D to simulate infrared scattered-light images of the inner part of protoplanetary disks with a dust pileup. We find that a dust pileup at the dead-zone inner edge, if present, casts a shadow extending out to ∼10 au. In the shadowed region the temperature significantly drops, which in some cases yields even multiple water snow lines. We also find that even without a dust pileup at the dead-zone inner edge, the disk surface can become thermally unstable, and the excited waves can naturally produce shadows and ring-like structures in observed images. This mechanism might account for the ring-like structures seen in the scattered-light images of some disks, such as the TW Hya disk.