The s-process in rotating asymptotic giant branch stars

Falk Herwig, Norbert Langer, Maria Anna Lugaro

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We discuss the occurrence of the s-process during the radiative interpulse phase of rotating AGB stars. Due to differential rotation, protons are mixed into C-12-rich layers after thermal pulses, in the course of the so called third dredge up episode. We follow the time evolution of key isotope abundances in the relevant layers with a post-processing code which includes time dependant mixing and nucleosynthesis. In rotating AGB models, the mixing persists during the entire interpulse phase due to the steep gradient of angular velocity at the envelope-core interface. As the layers containing protons and C-12, which are formed this way, become hotter, a C-13-pocket is formed in a natural way. However, in this situation also N-14 is formed and spread over the entire C-13-pocket. We include the neutron consuming N-14(n,p) reaction in our network and determine to what extent it reduces the production of trans-iron elements. We propose that rotation may be responsible for the spread of efficiencies of the C-13 neutron source as required by observations
Original languageEnglish
Pages (from-to)1056 - 1073
Number of pages18
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 2003
Externally publishedYes

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