SIMBAD references

We present ultraviolet (UV) and optical spectropolarimetry of the post-asymptotic giant branch star HR 4049 (= HD 89353). The polarization is time-variable in both magnitude and position angle. The variations in the polarization are tied to the orbital period and the circumstellar reddening and, in the optical, appear to arise from Rayleigh scattering in a thin disc. However, the ultraviolet (λ ≲ 3000 Å) polarization shows the signature of scattering from material in a bipolar distribution. The near-UV (~ 2000-3000 Å) polarization has approximately 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 component.