HR 4049: temporal variations in the structure of the circumstellar material

We present ultraviolet (UV) and optical spectropolarimetry of the post-asym ptotic giant branch star HR 4049 (= HD 89353). The polarization is time-var iable in both magnitude and position angle. The variations in the polarizat ion are tied to the orbital period and the circumstellar reddening and, in the optical, appear to arise from Rayleigh scattering in a thin disc. Howev er, the ultraviolet (lambda less than or similar to 3000 Angstrom) polariza tion shows the signature of scattering from material in a bipolar distribut ion. The near-UV (approximate to 2000-3000 Angstrom) polarization has appro ximately the same position angle as the optical polarization and hence also arises from scattering in a disc. However, the component perpendicular to the disc is of unknown origin. We discuss possible sources for this compone nt.