Breaking the Ice: Planetesimal Formation at the Snowline

Abstract

Recently Saito & Sirono (2011) proposed that large ice aggregates which drift in- wards in protoplanetary disks break up during sublimation, ejecting embedded silicate particles. This would lead to a concentration of small solid particles close to the snow- line. In view of this model we carried out laboratory experiments where we observed freely levitating ice aggregates sublimating. We find that frequent break up is indeed very common. Scaled to a 10 cm aggregate about 2x10^4 small silicate aggregates might result. This supports the idea that sublimation of drifting ice aggregates might locally increase the density of small dust (silicate) particles which might more easily be swept up by larger dust aggregates or trigger gravitational instability. Either way this might locally boost the formation of planetesimals at the snowline.