Modeling the formation of the ${}^{13}$C neutron source in AGB stars

Abstract

A major source of uncertainty in AGB models is the partial-mixing process of hydrogen, required for the formation of the so-called ${}^{13}$C pocket. Among the attempts to derive a self-consistent treatment of this physical process, there are 2D and 3D simulations of magnetic buoyancy. The ${}^{13}$C pocket resulting from mixing induced by magnetic buoyancy extends over a region larger than those so far assumed, showing an almost flat ${}^{13}$C distribution and a negligible amount of ${}^{14}$N. Recently, it has been proved to be a good candidate to match the records of isotopic abundance ratios of $s$-elements in presolar SiC grains. However, up to date such a magnetic mixing has been applied in post-process calculations only, being never implemented in a stellar evolutionary code. Here we present new stellar models, performed with the 1-d hydrostatic FUNS evolutionary code, which include magnetic buoyancy. We comment the resulting $s$-process distributions and show preliminary comparisons to spectroscopic observations and pre-solar grains measurements.

4 pages, 2 figures, NPA IX proceedings. Accepted in JPCS

References in corpus (4)

• Barium Isotopic Composition of Mainstream Silicon Carbides from Murchison: Constraints for s-Process Nucleosynthesis in AGB Stars
• Correlated Strontium and Barium Isotopic Compositions of Acid-Cleaned Single Silicon Carbides from Murchison
• MHD and deep mixing in evolved stars. 1. 2D and 3D analytical models for the AGB
• s-Processing from MHD-induced mixing and isotopic abundances in presolar SiC grains

Cited by in corpus (1)

• The carbon star mystery: forty years later