Talk abstract details

There is at present no viable theory whereby a {\it single} star with M$_{MS}$ $<$ 2.4 $\pm$ 0.3 M$_\odot$ can initiate and sustain a ``superwind" ($\dot{M}$ $>$ 10$^{\mbox{-}5-\mbox{-}4}$ M$_\odot$ yr$^{-1}$) at the tip of the AGB, which is necessary for PN formation. However, we propose that a binary companion can not only shape the morphology of a PN, but more importantly provide the required mass loss rate enhancement to generate the superwind. We give an overview of our recently submitted binary population synthesis paper where we calculate PN formation rates from binary common envelopes (CE), mergers, tidally synchronized systems that avoid CE, gravitationally focused winds, and double degenerate systems. The predicted number of Galactic PN with radii $<$ 0.9 pc shaped {\it and ejected} by a binary companion is 7,600 $\pm$ 2,200, which is (65 $\pm$ 20)\% of the observationally-estimated number of Galactic PN. We demonstrate that the observed {\it close} CSPN binary fraction of 15-20\% is consistent with our overall binary fraction considering we predict {\it two} peaks at log P(days) $\sim$ 0 and 4 in the CSPN period distribution. Finally, we discuss the impact of binarity on the PN luminosity function, CS mass distribution, chemical abundances, etc., and why these distributions predicted in the binary scenario are close to observations while the single star paradigm produces distributions which are measurably discrepant.