Probing the magnetic field structure in the W3 molecular cloud

This paper presents polarization maps of the central 3' x 5' region of the W3 molecular cloud at far-infrared (60 and 100 mu m) and submillimeter (350 mu m) wavelengths. We use the multiwavelength polarization measurements to differentiate between the emission in warm and cool dust components. We in fer that the submillimeter observations trace a layer of cool dust with hig h column density, which we attribute to a large scale ridge of material. Th is ambient ridge has an orderly magnetic held with evidence for "hourglass" field structure; however, the held structure is qualitatively different in size and orientation compared to previous studies. The far-infrared measur ements are dominated by warm dust surrounding evolved H II regions or embed ded young stars. The warm dust, in contrast to the ridge, has a disrupted m agnetic field that varies rapidly in the plane of the sky and along the lin e of sight, suggesting that the field has been distorted by the expansion o f H II regions.