The First Stars: Formation Of Binaries And Small Multiples

We investigate the formation of metal-free, Population III (Pop III), stars within a minihalo at z similar or equal to 20, starting from cosmological initial conditions. We follow the collapsing gas in the center of the minihalo up to number densities of 10(12) cm(-3). We then study the protostellar accretion onto the initial hydrostatic core, which we represent as a growing sink particle. We continue our simulation for 5000 yr after the first sink particle has formed. During this time, a disk-like configuration is assembled around the first protostar. At the end of the simulation, a small multiple system has formed within this disk, dominated by a binary with masses similar to 40M(circle dot) and similar to 10M(circle dot). If Pop Ill stars were to form typically in binaries or small multiples, the standard model of primordial star formation, where single, isolated stars are predicted to form in minihalos, would have to be modified.