Multicolor polarimetry of Be stars

There are no strong cases of night-to-night variability, and the only star showing unmistakable changes in polarization from year to year over the nine years covered by the program is Pi Aquarii. Even though the observed sample spans a wide range in spectral type, vsini, and degree of intrinsic polarization, the normalized wavelength dependence of the polarization is surprisingly similar for all of the stars.

Analysis of the wavelength dependence of the variable polarization of {pi} Aqr in terms of a simple equatorial-disk model suggests that changes in the circumstellar electron number density alone may be sufficient to account for the observations, but it is not clear what real physical mechanism is involved. Addresses: McDavid D. mcdavid@pinet.aip.org Limber Observatory, Timber Creek Road, P.O. Box 63599, Pipe Creek,Texas 78063 Explanatory