Evolution, nucleosynthesis and yields of low mass AGB stars at different metallicities (II): the FRUITY database

TL;DR

This paper introduces the FRUITY database, a comprehensive online resource for AGB star nucleosynthesis, providing detailed isotopic compositions and yields across different masses and metallicities, validated against observational data.

Contribution

The paper presents the first extensive, interactive database of AGB star nucleosynthesis yields, including detailed isotopic compositions and comparisons with observational data.

Findings

Theoretical [hs/ls] and [Pb/hs] ratios match observed trends.

Predicted C-star luminosity functions agree with observations.

Uncertainties in s-process predictions are discussed.

Abstract

By using updated stellar low mass stars models, we can systematically investigate the nucleosynthesis processes occurring in AGB stars, when these objects experience recurrent thermal pulses and third dredge-up episodes. In this paper we present the database dedicated to the nucleosynthesis of AGB stars: the FRUITY (FRANEC Repository of Updated Isotopic Tables & Yields) database. An interactive web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 < M/Msun < 3.0 and metallicities 1e-3 < Z < 2e-2, is discussed here. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parametrization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the third dredge-up efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find a good agreement with observations.