Galactic globular clusters: Ideal laboratories to test stellar nucleosynthesis?

¹ Geneva Observatory, University of Geneva, chemin des Maillettes 51, 1290 Sauverny, Switzerland
² Laboratoire d'Astrophysique de Toulouse et Tarbes, CNRS UMR 5572, Université Paul Sabatier Toulouse 3, 14 Av. E. Belin, 31400 Toulouse, France

Abstract

Galactic globular cluster (GC) stars exhibit abundance patterns which are not shared by their field counterparts, namely the well-documented C-N, O-Na and Mg-Al anticorrelations. Recent observations provided compelling evidence that these abundance anomalies were already present in the intracluster gas from which the presently observed stars formed. A widely held hypothesis is that the gas was polluted early in the history of the GC by material processed through H-burning at high temperature and then lost by stars more massive than the observed long-lived stars. However the “polluters" have not been unambiguously identified yet. Most studies have focused on AGB stars, but rotating massive stars present an interesting alternative. Here we critically analyse the pros and cons of both potential stellar polluters. We discuss the constraints that the observational data bring on stellar nucleosynthesis and hydrodynamics as well as on nuclear reaction rates and we try to answer to the following question: “Are GC ideal laboratories to test stellar nucleosynthesis and hydrodynamics?"