# NuGrid stellar data set - III. Updated low-mass AGB models and s-process nucleosynthesis with metallicities Z=0.01, Z=0.02 and Z=0.03

## TL;DR

This paper updates low-mass AGB stellar models with an improved mixing approach, leading to better agreement with observed s-process element abundances and providing comprehensive nucleosynthesis data for various metallicities.

## Contribution

It introduces an updated convective boundary mixing model in AGB star simulations, expanding the NuGrid data set with wider 13C-pockets and detailed nucleosynthesis results across multiple metallicities.

## Key findings

- Wider 13C-pocket improves agreement with observations
- Updated models produce detailed nucleosynthesis yields
- Data sets are available online for further research

## Abstract

The production of the neutron-capture isotopes beyond iron that we observe today in the solar system is the result of the combined contribution of the r-process, the s- process and possibly the i-process. Low-mass AGB (2 < M/Msun < 3) and massive (M >10 Msun ) stars have been identified as the sites of the s-process. In this work we consider the evolution and nucleosynthesis of low-mass AGB stars. We provide an update of the NuGrid Set models, adopting the same general physics assumptions but using an updated convective-boundary mixing model accounting for the contribution from internal gravity waves. The combined data set includes the initial masses Mzams/Msun = 2, 3 for Z = 0.03, 0.02, 0.01. These models are computed with the MESA stellar code and the evolution is followed up to the end of the AGB phase. The nucleosynthesis was calculated for all isotopes in post-processing with the NuGrid mppnp code. The convective boundary mixing model leads to the formation of a 13C-pocket three times wider compared to the one obtained in the previous set of models, bringing the simulation results now in closer agreement with observations. We also discuss the potential impact of other processes inducing mixing, like rotation, adopting parametric models compatible with theory and observations. Complete yield data tables, derived data products and online analytic data access are provided.