Turbulent Thermal Diffusion: A Way to Concentrate Dust in Protoplanetary Discs

TL;DR

This paper explores turbulent thermal diffusion in protoplanetary discs, showing how it can concentrate dust particles in cold regions, potentially aiding planetesimal formation.

Contribution

The study rederives turbulent thermal diffusion in astrophysical terms and demonstrates its significant role in particle concentration within protoplanetary discs.

Findings

Particles can be concentrated by factors of tens due to turbulent thermal diffusion.

This process could facilitate the streaming instability and planetesimal formation.

Turbulent thermal diffusion may be a key mechanism in early planetary system development.

Abstract

Turbulence acting on mixes of gas and particles generally evenly diffuses the latter through the former. However, in the presence of background gas temperature gradients a phenomenon known as turbulent thermal diffusion appears as a particle drift velocity (rather than a diffusive term). This process moves particles from hot regions to cold ones. We rederive turbulent thermal diffusion using astrophysical language and demonstrate that it could play a major role in protoplanetary discs by concentrating particles by factors of tens. Such a concentration would set the stage for collective behavior such as the streaming instability and hence planetesimal formation.