Protostars and Planets VI, Heidelberg, July 15-20, 2013
Formation of asteroid belts in particle-enriched regions of protoplanetary discs
Carrera, Daniel (Lund University)
Johansen, Daniel (Lund University)
Davies, Melvyn (Lund University)
There is mounting evidence that the traditional picture of the formation of asteroids must be revised. The size distribution of asteroids is hard to reconcile with a bottom-up formation scenario. Instead, asteroids may form top-down, with large 100-1000 km sized objects forming first by the gravitational collapse of dense clumps of small particles. In this work, we model the dynamics of solid particles in the disc, ranging from sub-mm sizes up to meter sizes.
Our results show that very small particles (chondrule-sized at 3 AU) can form dense clumps in the disc whenever there is a high solids-to-gas ratio (8 times solar value) or a reduced pressure support. We further show that these particle clumps can reach the disc Roche density, where gravitational collapse is expected to take place. Alternatively, these dense particle clumps may be the sites of enhanced coagulation, as our results show reduced particle speeds inside these clumps.
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