INFRARED POLARIMETRY OF RADIO LUMINOUS OH IR STARS

Polarimetry from 1 to 2.5 μm is presented for 14 radio luminous OH/IR stars. All of the stars show significant polarization. Four stars show only interstellar polarization, four show a combination of interstellar and intrinsic polarization, and six were too red to measure at any wavelength other than 2.2 μm. The interstellar polarization is substantial, and clearly indicates that interstellar extinction is a significant factor in the observed energy distributions of these stars. The intrinsic component is also substantial, and requires large asymmetries in the geometry of the circumstellar dust shells.