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| Paper: |
Ionization and its Structural Impacts on the Evolution of Planetary Nebulae |
| Volume: |
313, Asymmetrical Planetary Nebulae III |
| Page: |
283 |
| Authors: |
Schoenberner, D.; Steffen, M.; Jacob, R. |
| Abstract: |
We review our present knowledge about the formation and evolution of planetary nebulae and evaluate the relative importance of photoionization and wind interaction. It turns out that heating by photoionization drives the expansion of a planetary nebula during its entire life, while wind interaction accelerates and shapes the inner regions only during the later stages of evolution. We found observational evidence that the transition from spherical AGB-wind structures to more aspherical ones must occur when the star begins to evolve slowly off the AGB. |
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