SCUBA polarisation observations of the magnetic fields in prestellar cores

Prestellar cores represent the stage of star formation immediately prior to protostellar collapse. We present polarisation maps of three prestellar cores, L183, L1544 and L43. In each case the magnetic field lines are uniform but not parallel to the semi-minor axis of the core. This suggests that magnetic and thermal pressure support alone are inconsistent with the data. We also calculate the magnetic field strength using the Chandrasekhar-Fermi technique and find that all three cores are magnetically supercritical by a factor of ∼ 2. This is consistent with the observation that the magnetic field is not dominating the evolution of these cores.