Accretion of eroding pebbles and planetesimals in planetary envelopes

TL;DR

This paper investigates how wind erosion affects the accretion of pebbles and planetesimals onto planetary bodies, showing erosion reduces accretion efficiency especially for small bodies around 10 meters in size.

Contribution

It introduces a numerical model to study wind erosion's impact on accretion processes, highlighting the significance of erosion thresholds and planetary parameters.

Findings

Erosion significantly decreases accretion efficiency below ~10 m size.

The threshold size increases with planet radius and decreases with semi-major axis.

Atmospheric pressure up to 1 bar has minor influence on erosion effects.

Abstract

Wind erosion is a destructive mechanism that completely dissolves a weakly bound object like a planetesimal into its constituent particles, if the velocity relative to the ambient gas and the local gas pressure are sufficiently high. In numerical simulations we study the influence of such wind erosion on pebble and planetesimal accretion by a planetary body up to $10 R_\mathrm{Earth}$. Due to the rapid size reduction of an in-falling small body, the accretion outcome changes significantly. Erosion leads to a strong decrease in the accretion efficiency below a threshold size of the small body on the order of 10 m. This slows down pebble accretion significantly for a given size distribution of small bodies. The threshold radius of the small body increases with increasing planet radius and decreases with increasing semi-major axis. Within the parameters studied, an additional planetary atmosphere (up to 1 bar) is of minor importance.