A Mechanism for the Production of Jets and Ansae in Planetary Nebulae

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Abstract
Many elliptical planetary nebulae (PNs) exhibit pairs of small, low-ionization structures called "jets" and ansae, which are characterized by their equal and opposite displacements (0.01-0.03 pc) and redshifts (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 descriptors, which include an accelerating fast wind and a toroidal slow-wind mass-loss geometry to form elliptical PNs, we find a wide range of conditions under which jets and ansae can develop. We show that the expected sizes, velocities, and ionization of these microstructures conform quite nicely to observations.