Collisional properties of cm-sized high-porosity ice and dust aggregates and their applications to early planet formation

In dead zones of protoplanetary discs, it is assumed that micrometre-sized particles grow Brownian, sediment to the midplane and drift radially inward. When collisional compaction sets in, growing aggregates collect slower therefore dynamically smaller particles. This sedimentation growth phase highly porous ice dust simulated with laboratory experiments in which we obtained mm- cm-sized a porosity 90\% as well agglomerates 85\%. We modelled process during an analytical calculation compute agglomerate sizes when they reach disc. midplane, form thin dense layer gain relative velocities by, e.g., streaming instability or onset shear turbulence. To investigate also these collisions, performed additional drop tower high-porosity formed sedimentary-growth determined their mechanical parameters, including sticking threshold velocity, important for further evolution on way planetesimals. Finally, developed method calculate packing-density-dependent fundamental properties our agglomerates, Young's modulus, Poisson ratio, viscosity bulk from compression measurements. With was possible derive coefficient restitution fits order physically describe outcomes, applied collision model. this model, predictions about general dust-aggregate collisions are possible.