SUBMILLIMETER POLARIMETRIC OBSERVATIONS OF S140 AND GL2591 - INVESTIGATING THE ROLE OF VIEWING ANGLE ON OBSERVED POLARIZATION POSITION ANGLES

We have measured the 800 mu m polarization at three positions towards S140 and at the flux peak towards GL2591. For both sources the implied magnetic field direction is neither parallel nor perpendicular to the outflow axis, implying an (in-between) situation. A review of publish ed submillimetre polarimetric observations of outflow sources implies this scenario is common. Whilst beamsize effects are not thought to be critical, comparison of these observations with the results from a re cent theoretical model (Bonifacio & Emerson 1995) imply that the 'in-b etween' situations may actually be due to the effect of viewing angle on the observed polarization position angle. If the local magnetic fie ld is uniform and perpendicular to the outflow axis the observed posit ion angle of polarization for dichroic emission of aligned grains is h ighly dependent on the viewing angle. The surprising agreement between mid-infrared and submillimetre emissive polarization position angles for W3-IRS5, NGC7538-IRS1 and OMC1-IRc2, and their non-orthogonality t o the mid-IR absorptive polarization position angles, has implications for the magnetic field configuration around these outflow sources. In particular, an hour-glass magnetic field geometry may be applicable.