Red and infrared polarimetry of highly reddened stars in the galactic plane

We present VRIJHK polarimetry and JHK photometry of highly reddened stars found in an objective prism survey published by Stephenson [AJ, 103, 263 (1992)]. The JHK colors of these stars are consistent with interstellar extinction as the dominant source of the reddening. The distribution of the polarization position angles in Galactic coordinates is very similar to previous optical polarimetry surveys such as Mathewson & Ford [MNRAS, 74, 139 (1970)]. However, for the redder stars with IR polarimetry, the polarization strength is moderately lower than expected for the amount of extinction. We postulate that the line of sight to many of these stars samples specific regions where the grain population has poor polarizing properties, while the remainder of the line of sight is similar to the paths sampled by previous optical surveys. The wavelength dependence of the polarization from 1-2.5 μm for this sample of stars shows weak evidence for a greater departure from the mean for interstellar polarization than for most published near-infrared polarimetry.