Prompt planetesimal formation beyond the snow line

Abstract

We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to mm-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity--stopping time space whose only substantial dependence is on the disk's angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, ${\dot{M}}_p/\dot{M}>3\times 10^{-2}$ for $\alpha =10^{-2}$), that could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Including turbulent diffusion and vapor condensation processes numerically, we find that a modest enhancement of solids near the snow line occurs for cm-sized particles, but that this is largely immaterial for planetesimal formation. We note that radial drift couples planetesimal formation across radii in the disk, and suggest that considerations of planetesimal formation favor a model in which the initial deposition of material for giant planet cores occurs well beyond the snow line.

ApJ Letters, in press

References in corpus (5)

• The stickiness of micrometer-sized water-ice particles
• How to form planetesimals from mm-sized chondrules and chondrule aggregates
• Dust dynamics during protoplanetary disc clearing
• Planet formation bursts at the borders of the dead zone in 2D numerical simulations of circumstellar disks
• Can dust coagulation trigger streaming instability?

Cited by in corpus (9)

• Planetesimal formation starts at the snow line
• Formation of planetary systems by pebble accretion and migration: Growth of gas giants
• Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line
• Rocky super-Earths or waterworlds: the interplay of planet migration, pebble accretion and disc evolution
• Building the Galilean moons system via pebble accretion and migration: A primordial resonant chain
• Self-Induced Dust Traps Around Snow Lines in Protoplanetary Discs
• Enrichment of Jupiter's atmosphere by late planetesimal bombardment
• An analysis of binary microlensing event OGLE-2015-BLG-0060
• A "no-drift" runaway pile-up of pebbles in protoplanetary disks II. Characteristics of the resulting planetesimal belt