A& A Supplement series, Vol. 123, June I 1997, 241-272
Received April 22; accepted July 30, 1996
M. Forestini - C. Charbonnel
Send offprint request: M. Forestini
Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9, France
Laboratoire d'Astrophysique de Toulouse, CNRS UMR 5572, Toulouse, France
The structural and nucleosynthetic evolution of 3, 4, 5, 6 and stars with two metallicities (Z = 0.005 and 0.02) has been computed in detail, from the early pre-main sequence phase up to the thermally pulsing (TP) AGB phase or the onset of off-center carbon burning. Typically 10 to 20 thermal pulses have been followed for each TP-AGB object. This homogeneous and quite large set of models allows us to present an overview of the thermal pulse properties as well as of the nucleosynthesis accompanying the TP-AGB phase of intermediate-mass stars.
More specifically, after a brief description of the previous evolutionary stages, predictions are given for the isotopic ratios involving C, N, O, Ne, Mg, Al and Si. Also the surface abundances of , and are reported. As the asymptotic phase of the thermal pulses has been reached for each star, we also indicate how these abundances will probably evolve until the stars completely loose their envelope, by including the evolution of the nucleosynthesis itself.
keywords: stars: AGB -- stars: interiors -- stars: nucleosynthesis - stars: abundances