1997A&A...318..561K

In this paper we discuss the morphology of two bipolar planetary nebulae (PNe) based on broad-band (ESO/SERC) and narrow-band ([OIII] and H_α) images. At first sight both objects are similar and show two pronounced bright knots - the usual signature of a torus seen edge-on. We demonstrate though that the two objects are not two of a kind at this point but are rather representing two different stages of evolution. The brightness distribution found in Wei1-5 is well explained by a homogeneous torus with a ratio of radius to thickness of 2. KeWe1 is a complicated object showing point symmetry. It can be understood in terms of an incomplete ring, probably a torus caught in the process of breaking up due to the action of a strong wind from the central star.