MAGNETIC-FIELD COMPRESSION IN THE MON R2 CLOUD CORE

We have detected linear polarization of 800 mu m dust emission at four positions in the Mon R2 cloud core. The results confirm the previous suggestion of Hodapp (1987) that magnetic field lines are curved in this region. The curvature is consistent with field compression during super-critical collapse of the original cloud. A similar conclusion was reached from our previous study of the W3-IRS5 cloud core, and the size of the region where the field bends through 90 degrees is similar in each source (similar to 0.1-0.2 pc) The main difference is that the Mon R2 field is less pinched-in at the centre and this may be connected with the greater dispersion of the young stars in the Mon R2 core than in W3-IRS5. In both sources, there is evidence that the magnetic field in the cloud envelope is directly connected to that in the core, and also that the cloud field may channel the observed large-scale molecular outflows.