Speaker
Description
Pebbles, solid particles weakly coupled to the gas, are considered a key ingredient in planet formation, enabling both the onset of the streaming instability and the subsequent growth of planetary embryos through pebble accretion. For particles to partially decouple from the gas, they must be sufficiently compact. In contrast, the particles produced naturally from dust coagulation are highly porous fractal aggregates which remain tightly coupled to the gas. Understanding how these porous aggregates can be compacted into pebbles therefore remains an open problem in planet formation.
This compaction is the subject of active laboratory research. A new type of experiment is inspired by the conditions in particle-trapping eddies which occur in protoplanetary disks. These eddies are expected to locally enhance dust densities and collision rates and provide favorable conditions for aggregate growth and restructuring. In my ongoing master’s thesis, I investigate dust dynamics and aggregate growth in such trapping environments using numerical simulations.
I am developing an N-body simulation in C++ tracking particle motion and collisions, allowing aggregates to grow self-consistently. The model resolves individual collision events and follows the evolution of aggregate size, shape, and porosity under low-velocity conditions. Preliminary results show accelerated aggregate growth once local aggregate concentrations and collisional cross-sections increase, as well as the emergence of aggregate morphologies consistent with previous laboratory experiments. These results suggest a transition from gradual growth dominated by small-particle accretion to more stochastic growth through aggregate-aggregate collisions.
I highlight these early results, show the physical mechanisms driving aggregate growth, and outline planned extensions of the model to include additional gas-particle interactions relevant to disk environments, as well as comparisons with molecular-dynamics simulations of aggregates in gas. The simulation will be used to interpret and inform laboratory experiments on aggregate compaction and to connect experimental results to dust evolution in protoplanetary disks.
| Talk category | NOVA Network 2 |
|---|
