Protostellar discs formed from turbulent cores

We investigate the collapse and fragmentation of low-mass, trans-sonically turbulent pre-stellar cores, using smoothed particle hydrodynamics simulations. The initial conditions are slightly supercritical Bonnor-Ebert spheres, all with the same density profile, the same mass (M(O) = 6.1 M(circle dot)) and the same radius (R(O) = 17 000 au), but having different initial turbulent velocity fields. 400 turbulent velocity fields have been generated, all scaled so that the mean Mach number is M = 1. Then, a subset of these (in total 11 setups), having a range of net angular momenta, j, has been evolved. The evolution of these turbulent cores is significantly different from the collapse of a rigidly rotating core. It is not strongly correlated with j. Instead, it is moderated by the formation of filamentary structures due to converging turbulent flows. A high fraction (9 out of 13, similar to 69 per cent) of the individual protostars forming from turbulent cores are attended by resolved (R >= 10 au) protostellar accretion discs, but only a very small fraction (1 out of 9, similar to 11 per cent) of these discs is sufficiently cool and extended to develop non-linear gravitational instabilities and fragment. Protostars with discs show two distinct growth modes. They initially grow by direct gravitational collapse, followed by subsequent disc accretion.