Dynamics of self-gravitating dust clouds and the formation of planetesimals

Due to the gravitational force, clouds of dust and gas in the interstellar medium can contract and form stars and planet systems. Here we show that if the dust grains are electrically charged then the self-gravitation can be balanced by the “electrostatic pressure” and the collapse can be halted. In this case, the dust cloud may form soft dust planets, having the weight of a small moon or satellite, but a radius larger than of our Sun. There exist a critical mass beyond which the dust cloud collapses and forms a solid planet. We here present a simple model for the dynamics and equilibrium of self-gravitating dust clouds and apply the model to typical parameters for dust in molecular clouds and in the interstellar medium.