Attraction of Dust Grains in a Nebula

The study of attraction of dust grains in a plasma is one of the most active field of research in dusty plasmas. In this work, we proceed further with the investigation of the role of the attractive electrostatic force in the gravitational collapse to form stars or planets. We consider the mixture of dust and gas in the nebula surrounding an already formed star. First, at every point in the nebula we solve self-consistently the ionization equilibrium equation (balancing the ionizations due to the radiation field of the star with radiative recombinations) and the equation of radiation transfer (stellar and diffuse). This yields the plasma density and die radiation field in the nebula, when no dust is present in the nebula. Second, we include in the analysis the contribution of cosmic radiation in addition to the stellar one. Third, we study the charging and shielding processes for the dust grains in the nebula and determine the regions where the attractive electrostatic force is important.