Vorschau

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Abstract

When the protostellar nebula collapses to form a star, some of the gas and dust is left in the form of a protoplanetary disk. Exactly how the subsequent formation of planetesimals proceeds is still not fully understood, but the coagulation of the dust is believed to play a vital role. One of the main problems with this picture is that a number of barriers have been identified, at which bouncing, fragmentation and radial drift prevent the formation of large bodies.

We have investigated via theoretical models how large dust grains can grow in the presence of these barriers. This was done by examining some of the many assumptions that are generally used in the dust evolution modeling. We implemented a realistic model for the outcome of dust collisions, and we also studied the effect of velocity distributions and particle clumping, as well as the fate of large dust grains that drift inwards towards the star. In this process, we identified a new channel for planetesimal formation, and describe the initial steps towards an inside-out formation model where we give a prediction of the size and spatial distribution of the first generation of planetesimals.