Multipolar planetary nebulae: Not as geometrically diversified as thought

Abstract

Abstract. We present a general three-dimensional model of multipolar planetary nebulae (PNe). By rotating to different viewing angles and adjusting the angles between the multiple lobes, we demonstrate that the model is able to reproduce HST Hα images of 20 multipolar young PNe. Though this model only considers the geometrical projection effects, it significantly unifies the selected PNe and can be considered as a first-order fundamental model of the "multipolar" morphological class. This kind of model reduces complexity and is essential to pursuing of the shaping mechanism. In addition, we illustrate that under some special conditions, i.e. in certain viewing angles, or with low sensitivity, it will be hard to imagine that the projected image originates from a multipolar-lobed model.