Abstract

I will review the various laboratory and microgravity experiments on
low-velocity dust-aggregate collisions and will present a systematic
description of the possible outcomes of such collisions. Depending on
the aggregate masses, mass ratios, porosities, and collision velocities,
we can distinguish between four types of sticking, two types of
bouncing, and three types of fragmentation (Güttler et al. 2010,
arXiv:0910.425). Careful interpolation between and extrapolation of the
experimental results into yet uncovered parameter space allows us to
describe the protoplanetary dust growth from initially micrometer-sized
grains in a self-consistent way, using a recently-developed Monte-Carlo
method (Zsom et al. 2010, arXiv:1001.0488). The results of the first
simulations show that bouncing is the dominant process after a rapid
initial growth stage, which limits the maximum aggregate sizes
achievable in protoplanetary disks to ~1 cm. The simulations also reveal
the growth path of the dust aggregates through the multi-parameter
space, which is being used to define new laboratory experiments. With
this bi-directional feedback between experiments and modeling, we are
able to refine the results of protoplanetary dust growth modeling and to
achieve solid data for the maximum size, the size distribution, and the
porosities of the aggregates.