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Astron. Astrophys. 346, L37-L40 (1999)

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Letter to the Editor

Mixing and nucleosynthesis in rotating TP-AGB stars

N. Langer 1, A. Heger 2, S. Wellstein 1 and F. Herwig 1

1 Institut für Physik, Universität Potsdam, Am Neuen Palais 10, D-14415 Potsdam, Germany
2 Astronomy and Astrophysics Department, University of California, Santa Cruz, CA 95064, USA

Received 19 April 1999 / Accepted 6 May 1999


We present the first evolutionary models of intermediate mass stars up to their thermal pulses which include effects of rotation on the stellar structure as well as rotationally induced mixing of chemical species and angular momentum. We find a significant angular momentum transport from the core to the hydrogen-rich envelope and obtain a white dwarf rotation rate comparable to current observational upper limits of [FORMULA].

Large angular momentum gradients at the bottom of the convective envelope and the tip of the pulse driven convective shell are shown to produce marked chemical mixing between the proton-rich and the 12C-rich layers during the so called third dredge-up. This leads to a subsequent production of 13C which is followed by neutron production through 13C[FORMULA] n[FORMULA] in radiative layers in between thermal pulses. Although uncertainties in the efficiency of rotational mixing processes persist, we conclude that rotation is capable of producing a 13C-rich layer as required for the occurrence of the s-process in TP-AGB stars.

Key words: stars: evolution – stars: abundances – stars: AGB and post-AGB – stars: rotation

Send offprint requests to: N. Langer (ntl@astro.physik.uni-potsdam.de)

© European Southern Observatory (ESO) 1999

Online publication: June 17, 1999