Application of Magnetohydrodynamic Disk Wind Solutions to Planetary and Protoplanetary Nebulae

Abstract

Winds from accretion disks have been proposed as the driving source for precessing jets and extreme bipolar morphologies in Planetary Nebulae (PNe) and proto-PNe (pPNe). In this paper we address the applicability MHD disk wind models to PNe and pPNe. We first review Pelletier & Pudritz's (1992) non self-similar approach to magneto-centrifugal disk winds. We then discuss conditions which may occur in PNe and pPNe accretion disks that form via binary interactions. Finally, examining conditions on dimensionless parameters needed for the magneto-centrifugal disk wind model, we show that such winds can recover the observed momentum and energy input rates for PNe and pPNe. High accretion rates ($M_a \approx 10^{-4}$ \mdot) may be required in the latter case. We find that the observed {\it total} energy and momentum in pPNe can be recovered with disk wind models using existing disk formation scenarios. When combined with existing scenarios for accretion disk formation from disrupted stellar companions, our models may provide an explanation for the existence of high speed polar knots (FLIERS) observed in some PNe.