  The growth processes from protoplanetary dust to planetesimals are not fully
understood. Laboratory experiments and theoretical models have shown that
collisions among the dust aggregates can lead to sticking, bouncing, and
fragmentation. However, no systematic study on the collisional outcome of
protoplanetary dust has been performed so far so that a physical model of the
dust evolution in protoplanetary disks is still missing. We intend to map the
parameter space for the collisional interaction of arbitrarily porous dust
aggregates. This parameter space encompasses the dust-aggregate masses, their
porosities and the collision velocity. With such a complete mapping of the
collisional outcomes of protoplanetary dust aggregates, it will be possible to
follow the collisional evolution of dust in a protoplanetary disk environment.
We use literature data, perform own laboratory experiments, and apply simple
physical models to get a complete picture of the collisional interaction of
protoplanetary dust aggregates. In our study, we found four different types of
sticking, two types of bouncing, and three types of fragmentation as possible
outcomes in collisions among protoplanetary dust aggregates. We distinguish
between eight combinations of porosity and mass ratio. For each of these cases,
we present a complete collision model for dust-aggregate masses between 10^-12
and 10^2 g and collision velocities in the range 10^-4 to 10^4 cm/s for
arbitrary porosities. This model comprises the collisional outcome, the
mass(es) of the resulting aggregate(s) and their porosities. We present the
first complete collision model for protoplanetary dust. This collision model
can be used for the determination of the dust-growth rate in protoplanetary
disks.
