Planetesimal formation around the snow line: I. Monte Carlo simulations of silicate dust pile-up in a turbulent disk

Abstract

Context: The formation of rocky planetesimals is a long-standing problem in planet formation theory. One of the possibilities is that it results from gravitational instability as a result of pile-up of small silicate dust particles released from sublimating icy pebbles that pass the snow line. Aims: We want to understand and quantify the role of the water snow line for the formation of rock-rich and ice-rich planetesimals. In this paper, we focus on the formation of rock-rich planetesimals. A companion paper examines the combined formation of both rock-rich and ice-rich planetesimals. Methods: We develop a new Monte Carlo code to calculate the radial evolution of silicate particles in a turbulent accretion disk, accounting for the back-reaction (i.e., inertia) of the particles on their radial drift velocity and diffusion. Results depend in particular on the particle injection width (determined from the radial sublimation width of icy pebbles), the pebble scale height and the pebble mass flux through the disk. The scale height evolution of the silicate particles, which is the most important factor for the runaway pile-up, is automatically calculated in this Lagrange method. Results: From the numerical results, we derive semi-analytical relations for the scale height of the silicate dust particles and the particles-to-gas density ratio at the midplane, as functions of a pebble-to-gas mass flux ratio and the $\alpha$ parameters for disk gas accretion and vertical/radial diffusion. We find that the runaway pile-up of the silicate particles (formation of rocky planetesimals) occurs if the pebble-to-gas mass flux ratio is $>[({\alpha }_{Dz}/{\alpha }_{acc})/3\times 10^{-2}{]}^{1/2}$ where ${\alpha }_{Dz}$ and ${\alpha }_{acc}$ are the $\alpha$ parameters for vertical turbulent diffusion and disk gas accretion.

15 pages, accepted for publication in Astronomy & Astrophysics

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Cited by in corpus (13)

• Forming pressure-traps at the snow-line to isolate isotopic reservoirs in the absence of a planet
• Planetesimal Initial Mass Functions following Diffusion Regulated Gravitational Collapse
• Planetesimal formation around the snow line. II. Dust or pebbles?
• A global two-layer radiative transfer model for axisymmetric, shadowed protoplanetary disks
• Modeling the Evolution of Silicate/Volatile Accretion Discs around White Dwarfs
• On the Origin of Dust Structures in Protoplanetary Disks: Constraints from the Rossby Wave Instability
• Dust Accumulation near the Magnetospheric Truncation of Protoplanetary Discs around T Tauri Stars
• A "no-drift" runaway pile-up of pebbles in protoplanetary disks in which midplane turbulence increases with radius
• Monte Carlo Simulation of Dust Particles in a Protoplanetary Disk: Crystalline to Amorphous Silicate Ratio in Comets
• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks II: Dust Ring Formation Mediated by Backreaction and Fragmentation
• Effects from different grades of stickiness between icy and silicate particles on carbon depletion in protoplanetary disks
• Ionizing Protoplanetary Disks in Pebble Collisions
• A "no-drift" runaway pile-up of pebbles in protoplanetary disks II. Characteristics of the resulting planetesimal belt