The role of discs in the formation of binary and multiple star systems

We consider the dynamical evolution of a small number of protostars formed by the fragmentation of a dense molecular cloud core, taking into account in a simplified way the dissipative encounters between the protostars caused by the presence of their concomitant circumstellar discs. For an initial system of two stars, the resulting binary parameters are determined essentially by the initial angular momentum and to a lesser extent by the rate at which the accretion discs evolve. For an initial system of three stars, however, a narrow range of initial conditions leads to a broad spread of final configurations. (author)