Globular cluster abundances in the light of 3D hydrodynamical model atmospheres

Abstract

The new generation of 3D hydrodynamical model atmospheres have been employed to study the impact of a realistic treatment of stellar convection on element abundance determinations of globular cluster stars for a range of atomic and molecular lines. Due to the vastly different temperature structures in the optically thin atmospheric layers in 3D metal-poor models compared with corresponding hydrostatic 1D models, some species can be suspected to be hampered by large systematic errors in existing analyses. In particular, 1D analyses based on minority species and low excitation lines may overestimate the abundances by >0.3 dex. Even more misleading may be the use of molecular lines for metal-poor globular clusters. However, the prominent observed abundance (anti-)correlations and cluster variations are largely immune to the choice of model atmospheres.