Convective-reactive nucleosynthesis of K, Sc, Cl and p-process isotopes in O-C shell mergers
Abstract
We address the deficiency of odd-Z elements P, Cl, K and Sc in Galactic chemical evolution models through an investigation of the nucleosynthesis of interacting convective O and C shells in massive stars. 3D hydrodynamic simulations of O-shell convection with moderate C-ingestion rates show no dramatic deviation from spherical symmetry. We derive a spherically averaged diffusion coefficient for 1D nucleosynthesis simulations, which show that such convective-reactive ingestion events can be a production site for P, Cl, K and Sc. An entrainment rate of 10-3 M⊙ s-1 features overproduction factors OPs ≈ 7. Full O-C shell mergers in our 1D stellar evolution massive star models have overproduction factors OPm > 1 dex but for such cases 3D hydrodynamic simulations suggest deviations from spherical symmetry. γ-process species can be produced with overproduction factors of OPm > 1 dex, for example, for 130, 132Ba. Using the uncertain prediction of the 15 M⊙, Z = 0.02 massive star model (OPm ≈ 15) as representative for merger or entrainment convective-reactive events involving O- and C-burning shells, and assume that such events occur in more than 50 per cent of all stars, our chemical evolution models reproduce the observed Galactic trends of the odd-Z elements.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2018
- DOI:
- 10.1093/mnrasl/slx126
- arXiv:
- arXiv:1704.05985
- Bibcode:
- 2018MNRAS.474L...1R
- Keywords:
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- stars: abundances;
- stars: evolution;
- stars: interiors;
- physical data and processes: hydrodynamics;
- Galaxy: abundances;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 6 pages, 6 figures, accepted for publication in MNRAS