THE MAGNETIC-FIELD IN THE SAGITTARIUS B2 CLOUD

We present the results of the first study of polarized submillimetre e mission from the Sgr B2 giant molecular cloud. Detections were obtaine d for six out of 10 positions studied, with percentage polarizations o f 0.8-2.6 per cent. For five of the positions, the polarization vector s are aligned at an angle close to 15-degrees east of north, indicatin g a global magnetic field oriented approximately east-west. This direc tion is perpendicular to the long axis of the cloud, suggesting infall of material primarily down the field lines, in agreement with theoret ical models. A polarization 'hole' is found towards two high-mass embe dded objects, as has previously been observed in other molecular cloud s; the most likely explanation for Sgr B2 is a change in field directi on in the cores away from the plane of the sky.