Infrared polarimetry of dark clouds – III. The relationship between the magnetic field and star formation in the NGC 1333 region

We have measured the K-band polarization of 15 infrared sources toward the NGC 1333 region. The distribution of the position angles of polarization vectors is bimodal: one component, composed of the majority (80 per cent) of the observed infrared sources, has a centre at a position angle of 125°±30°, while the other component, composed of three sources (HH7–11 IRS, SGS 1 and LkHα271), shows position angles of 40°±20°, nearly perpendicular to the first. We assign the origin of the former component to the magnetic field threading the NGC 1333 region, and that of the latter to anisotropic reflection nebulosity associated with those young stellar objects. The perpendicularity of the position angles between field stars and young stellar objects suggests that star formation and cloud evolution in the NGC 1333 region might have occurred under the influence of the magnetic field: the parent molecular cloud has contracted preferentially along the field, resulting in a flattened shape, and subsequently, when circumstellar discs are formed, their planes are constrained to lie orthogonal to the field.