ULTRAVIOLET SPECTROPOLARIMETRY OF THE BE STAR PP CARINAE WITH THE WISCONSIN ULTRAVIOLET PHOTO-POLARIMETER EXPERIMENT

We present the first ultraviolet spectropolarimetric observations of t he Be star PP Car, obtained with the Wisconsin Ultraviolet Photo-Polar imeter Experiment (WUPPE) aboard the Astro 1 mission. Usable polarizat ion data were obtained from 1400 to 2330 angstrom, along with a good s pectrum from 1400 to 3200 angstrom. These data show a lower polarizati on shortward of the Balmer jump than had been predicted by standard mo dels, and a broad UV polarization dip around 1900 angstrom is seen. Th ese results are in agreement with those found from the WUPPE observati ons of two other Be stars, zeta Tau and pi Aqr, which were published e arlier. All these observations are an important probe of the Be circum stellar envelopes and demonstrate the need for the inclusion of metal- line effects in circumstellar disk models of Be star UV polarization.