On the Feeding Zone of Planetesimal Formation by the Streaming Instability

TL;DR

This study uses large-scale simulations to identify the typical separation between filaments formed by the streaming instability, revealing the initial feeding zone size for planetesimal formation in protoplanetary disks.

Contribution

It provides the first large-scale simulation data showing the characteristic separation of filaments, advancing understanding of planetesimal formation zones.

Findings

Multiple filamentary concentrations with ~0.2 gas scale heights separation

Higher frequency of filament merging and splitting in larger domains

Separation distance exceeds linear stability analysis predictions

Abstract

The streaming instability is a promising mechanism to overcome the barriers in direct dust growth and lead to the formation of planetesimals. Most previous studies of the streaming instability, however, were focused on a local region of a protoplanetary disk with a limited simulation domain such that only one filamentary concentration of solids has been observed. The characteristic separation between filaments is therefore not known. To address this, we conduct the largest-scale simulations of the streaming instability to date, with computational domains up to 1.6 gas scale heights both horizontally and vertically. The large dynamical range allows the effect of vertical gas stratification to become prominent. We observe more frequent merging and splitting of filaments in simulation boxes of high vertical extent. We find multiple filamentary concentrations of solids with an average separation of about 0.2 local gas scale heights, much higher than the most unstable wavelength from linear stability analysis. This measures the characteristic separation of planetesimal forming events driven by the streaming instability and thus the initial feeding zone of planetesimals.