Enrichment of the Dust-to-Gas Mass Ratio in Bondi/Jeans Accretion/Cloud Systems due to Unequal Changes in Dust and Gas Incoming Velocities

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 from gas so that the dust-to-gas ratio is substantially enriched above the 1% interstellar medium (ISM) level.