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A& A Supplement series, Vol. 123, June I 1997, 241-272

Received April 22; accepted July 30, 1996

Nucleosynthesis of light elements inside thermally pulsing AGB stars

I. The case of intermediate-mass stars

M. Forestini tex2html_wrap10505 - C. Charbonnel tex2html_wrap10507

Send offprint request: M. Forestini

tex2html_wrap10509  Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9, France
tex2html_wrap10511  Laboratoire d'Astrophysique de Toulouse, CNRS UMR 5572, Toulouse, France


The structural and nucleosynthetic evolution of 3, 4, 5, 6 and tex2html_wrap_inline10491 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 tex2html_wrap_inline10495, tex2html_wrap_inline10497 and tex2html_wrap_inline10499 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

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