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Chemical Composition and Evolution of Post-AGB Stars
Published online by Cambridge University Press: 25 May 2016
Abstract
Analysis of the chemical compositions of post-AGB stars reveals the following abundance patterns: (i) Post-AGB stars which are extremely underabundant in Fe and other refractory elements, but which have nearly normal abundances of C, N, O, S, and Zn. The depleted refractory elements are locked up in circumstellar dust grains. Formation of dust close to the star, and dust-gas separation and dust-driven mass loss driving out mostly the dust may explain the abundances of these stars. (ii) High-latitude hot post-AGB stars which show an underabundance of carbon, indicating that they left the AGB before the third dredge-up occurred. (iii) Post-AGB stars with overabundances of carbon and s-process elements, indicating that they have gone through the third dredge-up and carbon-star phase on the AGB. The overabundance of Li, Al, C and s-process elements in some post-AGB stars indicate that they have gone through the dredge-up and Hot Bottom Burning nucleosynthesis at the base of the convective envelope. The observed characteristics of post-AGB stars indicate an evolutionary sequence in the transition region from the tip of the AGB into the young planetary nebula stage.
- Type
- Session V — Post-AGB Stars
- Information
- Symposium - International Astronomical Union , Volume 177: The Carbon Star Phenomenon , 2000 , pp. 225 - 236
- Copyright
- Copyright © Kluwer 2000