Dust diffusion and a new secular instability in disks: a way to create ring structures & planetesimals
Abstract
Recent ALMA observations with high spatial resolution have found dust rings and gaps in some protoplanetary disks. These axisymmetric substructures are thought to be related to the planet formation although the origin of these substructures is still debated. One of the promising mechanisms to form those rings is the secular gravitational instability (GI; Takahashi & Inutsuka 2016). The secular GI has also been proposed as a mechanism of the planetesimal formation since dust particles accumulate via the instability (Youdin 2011; Tominaga et al. 2018). The growth of the instability is suppressed by the dust diffusion, which was often modeled by a diffusion term in the continuity equation. This modeling, however, does not conserve the total angular momentum. We reformulated equations that properly describe the dust diffusion and conserve the angular momentum. Our formulation is based on the mean-field approximation. Using the formulated equations, we performed the linear analysis of dusty gas disks and found a new instability, which we refer to as two-component viscous gravitational instability (TVGI), besides the secular GI. TVGI is triggered by the dust-gas friction and the turbulent viscosity. We found that TVGI is another promising mechanism to form axisymmetric substructures and planetesimals since its growth leads to the accumulation of dust particles.
- Publication:
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From Stars to Planets II - Connecting our understanding of star and planet formation
- Pub Date:
- June 2019
- Bibcode:
- 2019fstp.confE..13T