A MECHANISM FOR THE PRODUCTION OF JETS AND ANSAE IN PLANETARY-NEBULAE

Many elliptical planetary nebulae (PNs) exhibit pairs of small, low-io nization structures called ''jets'' and ansae, which are characterized by their equal and opposite displacements (0.01-0.03 pc) and redshift s (50 km s(-1)) from the nucleus along the nebular symmetry axis. Here we propose that jets and ansae can quite easily develop prior to the onset of the fast wind during the proto-PN phase. Using nominal descri ptors, which include an accelerating fast wind and a toroidal slow-win d mass-loss geometry to form elliptical PNs, we find a wide range of c onditions under which jets and ansae can develop. We show that the exp ected sizes, velocities, and ionization of these microstructures confo rm quite nicely to observations.