Enrichment of the dust-to-gas mass ratio in Bondi/Jeans accretion/cloud systems due to unequal changes in dust and gas incoming velocities

TL;DR

This paper presents a model of cloud accretion combining Bondi and Jeans regimes, showing that dust-gas velocity differences lead to dust enrichment in the cloud, exceeding typical interstellar medium levels.

Contribution

It introduces a combined Bondi/Jeans accretion model that accounts for dust-gas velocity disparities, explaining dust enrichment in cloud systems.

Findings

Dust-to-gas ratio can be significantly increased due to dust pile-up.

The model predicts a smooth transition from wind-type to Bonnor-Ebert density profiles.

Dust enrichment surpasses the typical 1% ISM level.

Abstract

The ratio of the Bondi and Jeans lengths is used to develop a cloud-accretion model that describes both an inner Bondi-type regime where gas pressure is balanced by the gravity of a central star and an outer Jeans-type regime where gas pressure is balanced by gas self-gravity. The gas density profile provided by this model makes a smooth transition from a wind-type inner solution to a Bonnor-Ebert type outer solution. It is shown that high-velocity dust impinging on this cloud will tend to pile-up due to having a different velocity profile than gas so that the dust-to-gas ratio is substantially enriched above the 1% ISM level.