Sticking and Bouncing of Pre-planetary Dust Grains
T. Poppe, J. Blum, L. O. Heim (University of Jena, Germany)
The first step of planet formation is thought to be the growth of
micron-sized dust grains embedded in the dilute gas of the early solar
nebula. Inelastic collisions driven by Brownian motion for the
micron-sized pre-planetary dust particles and from differential
sedimentation and gas drag-induced orbital decay for mm-sized dust
aggregates result in the formation of planetesimals and
cometesimals, which are large enough to continue the growth by
gravitational attraction. While the state of the gas disk and the
motion of the particles therein is comparatively well known, research
on the collisional behavior of the dust grains and on the inter-particle
forces is lacking. We investigated the sticking properties of small
grains by simulation experiments with analogous materials. We will
present results of individual grain-target collisions and of the
measurement of inter-particle forces by atomic force microscopy and we
will point out discrepancies between theoretical models and our
measurements.