par Choplin, Arthur ;Goriely, Stéphane ;Siess, Lionel ;Martinet, Sébastien
Référence The European Physical Journal, 61, page (68)
Publication Publié, 2025-03-31
Article révisé par les pairs
Résumé : A complex interplay between mixing and nucleosynthesis is at work in asymptotic giant branch (AGB) stars. In addition to the slow neutron capture process (s-process), the intermediate neutron capture process (i-process) can develop during proton ingestion events (PIEs). In this paper, after quickly reviewing the different modes of production of heavy elements in AGB stars that have been identified so far, we investigate the synthesis of actinides and other short-lived radioactive nuclei (SLRs, 60Fe, 107Pd, 126Sn, 129I, 135Cs, and 182Hf) during i-process nucleosynthesis. AGB stellar models with initial masses 1≤Mini/M⊙≤3, metallicities -3≤ [Fe/H] ≤0, and different overshoot strengths were computed with the stellar evolution code STAREVOL. During PIEs, a nuclear network of 1160 isotopes is used and coupled to the transport equations. We found that AGB models with [Fe/H] <-2 can synthesize actinides with abundances sometimes greater than solar values. The 60Fe yield scales with the initial metallicity, while the 107Pd, 126Sn, 129I, 135Cs, and 182Hf yields follow a similar pattern as a function of metallicity, with a production peak at [Fe/H] ≃-1.3. At [Fe/H] <-1, the fraction of odd Ba isotopes fBa,odd is predicted to vary between 0.6 and 0.8 depending on the initial mass and metallicity. Nuclear uncertainties on our 1M⊙ [Fe/H] =-2.5 model lead to fBa,odd ranging between 0.27 and 0.76, which is clearly above the s-process value. AGB stars experiencing PIEs appear to be potential producers of actinides and SLRs, particularly at low metallicity (except for 60Fe). Galactic chemical evolution modelling is required to assess their possible contribution to the galactic enrichment.

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