Trapping of dust by coherent vortices in the solar nebula

TL;DR

This paper investigates how large-scale vortices in the solar nebula can trap dust particles, potentially leading to planetesimal formation, by deriving analytical models and analyzing the effects of turbulence and particle dynamics.

Contribution

It introduces an exact vortex solution for dust capture analysis and examines the influence of turbulence and different regimes on dust trapping efficiency.

Findings

Optimal dust capture occurs near Jupiter's orbit and the asteroid belt.

Vortices can concentrate dust sufficiently for gravitational collapse.

Capture efficiency varies with particle size and local turbulence conditions.

Abstract

We develop the idea proposed by Barge & Sommeria (1995) and Tanga et al. (1996) that large-scale vortices present in the solar nebula can concentrate dust particles and facilitate the formation of planetesimals and planets. We introduce an exact vortex solution of the incompressible 2D Euler equation and study the motion of dust particles in that vortex. In particular, we derive analytical expressions for the capture time and the mass capture rate as a function of the friction parameter. Then, we study how small-scale turbulent fluctuations affect the motion of the particles in the vortex and determine their rate of escape by solving a problem of quantum mechanics. We apply these results to the solar nebula and find that the capture is optimum near Jupiter's orbit (as noticed already by Barge & Sommeria 1995) but also in the Earth region. This second optimum corresponds to the transition between the Epstein and the Stokes regime which takes place, for relevant particles, at the separation between telluric and giant planets (i.e near the asteroid belt). At these locations, the particles are efficiently captured and concentrated by the vortices and can undergo gravitational collapse to form the planetesimals.