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| Paper: |
The Formation of Very Narrow Waist Bipolar Planetary Nebulae |
| Volume: |
199, Asymmetrical Planetary Nebulae II: From Origins to Microstructures |
| Page: |
125 |
| Authors: |
Rappaport, Saul |
| Abstract: |
We discuss the interaction of the slow wind blown by an asymptotic giant branch (AGB) star with a collimated fast wind (CFW) blown by its main sequence or white dwarf companion, at orbital separations in the range of several AU < ~ a < ~ 200AU. The CFW results from accretion of the AGB wind into an accretion disk around the companion. We argue that such systems are the progenitors of bipolar planetary nebulae and bipolar symbiotic nebulae with a very narrow equatorial waist between the two polar lobes. The CFW wind will form two lobes along the symmetry axis, and will further compress the slow wind near the equatorial plane, leading to the formation of a dense slowly expanding ring. We conduct a population synthesis study of the formation of planetary nebulae in wide binary systems which quantitatively supports the proposed model. The population synthesis code follows the evolution of both stars and their arbitrarily eccentric orbit, including mass loss via stellar winds, for 5×104 primordial binaries. We show the number of expected systems that blow a CFW is in accord with the number found from observations, to within the many uncertainties involved. Overall, we find that ~ 5% of all planetary nebulae are bipolars with very narrow waists. Our population synthesis not only supports the CFW model, but more generally supports the binary model for the formation of bipolar planetary nebulae. |
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