Visible and infrared continuum spectropolarimetric observations of ten OB and supergiant and O emission line stars

Low resolution optical wavelength spectropolarimetry (lambda5000 - lambda7000) and infrared filter polarimetry are presented for 10 O and B stars. The sample contains slow and rapid rotators, a range of spectral types, O6 - B2, and two known binaries. The optical data were obtained over a period of 3 years using the Pine Bluff Observing Facility of Washburn Observatory. The infrared data were acquired over the course of two nights with the 1.3m telescope of Kitt Peak National Observatory. Seven of the ten program stars exhibited random polarimetric fluctuations at the 0.2% - 0.4% level on time scales of several days to months. With the exception of one of the binary stars, the observed position angles varied with time in a way that implies that the intrinsic position angle itself is time dependent. For the majority of the polarimetrically variable stars, the interstellar component dominated the observed polarization vector making the interpretation difficult. In two cases, the intrinsic polarization and position angle were consistent with being constant with wavelength. In two other cases, the peculiar wavelength structure of the polarization evidenced a large intrinsic polarization, possibly comparable to the interstellar contribution, and may be wavelength dependent. For this small sample, polarization variations are large for slow rotators and objects with large Hα emission components. However, no detailed correlations of polarization variabililty with Hα variability or with spectral type is apparent. A sample interpretation is presented in terms of electron scattering off blobs imbedded in the stellar wind