The extreme initial kinetic energy allowed by a collapsing turbulent core

Abstract

We present high-resolution hydrodynamical simulations aimed at following the gravitational collapse of a gas core, in which a turbulent spectrum of velocity is implemented only initially. We determine the maximal value of the ratio of kinetic energy to gravitational energy, denoted here by (EkinEgrav)max, so that the core (i) will collapse around one free-fall time of time evolution or (ii) will expand unboundedly, because it has a value of Ekin/Egrav larger than (EkinEgrav)max. We consider core models with a uniform or centrally condensed density profile and with velocity spectra composed of a linear combination of one-half divergence-free turbulence type and the other half of a curl-free turbulence type. We show that the outcome of the core collapse are protostars forming either (i) a multiple system obtained from the fragmentation of filaments and (ii) a single primary system within a long filament. In addition, some properties of these protostars are also determined and compared with those obtained elsewhere.