Stellar structure and mass loss on the upper asymptotic giant branch |
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| Authors: | Noam Soker Amos Harpaz |
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| Institution: | Department of Physics, University of Haifa at Oranim, Oranim, Tivon 36006, Israel |
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| Abstract: | We examine the envelope properties of asymptotic giant branch (AGB) stars as they evolve on the upper AGB and during the early post-AGB phase. Because of the high mass-loss rate, the envelope mass decreases by more than an order of magnitude. This makes the density profile below the photosphere much shallower, and the entropy profile much steeper. We discuss the possible role of these changes in the profiles in the onset of the high mass-loss rate (superwind) and the large deviation from spherical mass loss at the termination of the AGB. We concentrate on the idea that the shallower density profile and steeper entropy profile allow the formation of cool magnetic spots, above which dust forms much more easily. |
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| Keywords: | stars: AGB and post-AGB circumstellar matter stars: magnetic fields stars: mass-loss planetary nebulae: general |
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