Growth of Dust as the Initial Step Toward Planet Formation

摘要: We discuss the results of laboratory measurements and theoretical models concerning aggregation dust in protoplanetary disks as initial step toward planet formation. Small particles easily stick when they collide form aggregates with an open, often fractal structure, depending on growth process. Larger are still expected to grow at collision velocities about 1 m/s. Experiments also show that, after intermezzo destructive velocities, high above 10 m/s porous materials again lead net target. Considerations dust-gas interactions that for not too different surface-to-mass ratio remain limited up sizes m, seems be guaranteed reach these quickly easily. For meter sizes, coupling nebula turbulence makes processes more likely. Global a turbulent nebula, small swept fast consistent observations disks. An extended phase may therefore exist during which particle component is kept alive through collisions driven by turbulence, frustrates planetesimals until conditions favorable one or reasons.