Near-infrared imaging polarimetry of bipolar nebulae. 3: R-Mon/NGC-2261
High-spatial-resolution polarization vector maps of NGC 2261 at J, H and K show a centrosymmetric pattern, suggesting that it is a near-infrared reflection nebula, illuminated by R Mon. Evidence indicates that R Mon is surrounded by a toroid or dense disk of material. This evidence includes the direction and constancy of the polarization position angle with wavelength, the low polarization seen immediately to the west and east of R Mon, and the increasing blueness of NGC 2261 with increasing angular distance from R Mon. Modeling of the radial dependence of polarization is consistent with the blueshifted outflow being a parabolic cavity, with the scattering of radiation taking place principally at the surface of this cavity.