Multipolar young planetary nebulae modelled as a precessing and orbiting jet with time-dependent ejection velocity




We have carried out 3D hydrodynamic simulations of precessing, variable ejection velocity bipolar jets in order to model multipolar protoplanetary (or planetary) nebulae. For these nebulae, we assume a binary source, with an asymptotic giant branch primary star which ejects an isotropic wind, and a companion which ejects the bipolar jet system. We find that it is possible to relate the large-scale morphological characteristics of these nebulae (lobe size, semi-aperture angle, number of observed lobes) to some of the parameters of the binary system, such as the ratio between the orbital and precession periods, the ratio between the masses of the binary components and the major axis of the elliptical orbit. Our results show that synthetic nebulae with well-defined lobe morphologies (resembling many of the observed multipolar planetary nebulae) are obtained from our models.