[ITAL]K[/ITAL][arcmin]-Band Polarimetric Imaging of S187 IR and S233

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Abstract
K'-band polarimetric images of star-forming regions S187 IR and S233 are presented. In S187 IR, a bipolar, near-infrared nebula is observed around IRAS 01202+6133, with the southern part being bright and knotty, and the northern part being faint and filamentary. The polarization pattern shows that the nebula is illuminated by a single near-infrared source, which is associated with IRAS 01202+6133. A polarization disk is found around this source with the disk plane roughly perpendicular to the axis of the bipolar nebula. We conclude that this source is the driving source of the outflow in the region. Two nebulae are detected in the S233 region. Associated with a compact infrared cluster, S233 A is roughly round in shape and shows a weak polarization pattern. The S233 B nebula shows roughly elongated geometry in the east-west direction. The polarization vectors divide it into three parts. Each part has distinctly different polarization from the others. The northeastern part of S233 B exhibits a centrosymmetric polarization pattern around a centroid, at which we locate a deeply embedded source (DES) undetected in the K' band and shorter wavelengths. The DES is likely the exciting source of water masers and outflows in the S233 B region. The western part of the nebula shows a parallel polarization pattern, but the southeastern part displays very little polarization. Comparison of the morphology and polarization of the nebulae in different star-forming regions suggests a close relationship between the evolutionary sequence of the young stellar objects and the morphology of the associated nebulae.

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