A view of the H-band light-element chemical patterns in Globular Clusters under the AGB self-enrichment scenario

TL;DR

This study supports the AGB self-enrichment scenario for globular cluster formation by showing that AGB star yields can reproduce observed light-element patterns across multiple clusters and metallicities.

Contribution

It provides a comprehensive analysis of AGB models matching observed chemical patterns in globular clusters, confirming the role of AGB stars in their chemical enrichment.

Findings

AGB yields match observed chemical patterns in GCs

Trend with metallicity aligns with AGB evolution models

AGB stars in the 4-8 solar mass range influence GC chemical enrichment

Abstract

We discuss the self-enrichment scenario by AGB stars for the formation of multiple populations in globular clusters (GCs) by analyzing data set of giant stars observed in 9 Galactic GCs, covering a wide range of metallicities and for which the simultaneous measurements of C, N, O, Mg, Al, Si are available. To this aim we calculated 6 sets of AGB models, with the same chemical composition as the stars belonging to the first generation of each GC. We find that the AGB yields can reproduce the set of observations available, not only in terms of the degree of contamination shown by stars in each GC but, more important, also the observed trend with metallicity, which agrees well with the predictions from AGB evolution modelling. While further observational evidences are required to definitively fix the main actors in the pollution of the interstellar medium from which new generation of stars formed in GCs, the present results confirm that the gas ejected by stars of mass in the range $4~\rm M_{\odot} \leq \rm M \leq 8~\rm M_{\odot}$ during the AGB phase share the same chemical patterns traced by stars in GCs.