The link between chemical anomalies along the red giant branch and the horizontal branch extension in globular clusters

TL;DR

This study reveals a strong empirical link between chemical abundance variations in red giant stars and the temperature extension of blue tails in the horizontal branch of globular clusters, suggesting a connection between stellar chemistry and evolutionary features.

Contribution

It provides the first clear empirical evidence connecting the Na-O anticorrelation in RGB stars with the temperature extension of the HB in globular clusters.

Findings

Longer O-depleted tails correlate with hotter HB stars

Chemical anomalies are linked to HB morphology

Supports star-to-star abundance variation influence on stellar evolution

Abstract

We find a strong correlation between the extension of the Na-O anticorrelation observed in red giant branch (RGB) stars and the high temperature extension of the horizontal branch (HB) blue tails of Galactic globular clusters (GCs). The longer is the O-depleted tail of the Na-O anticorrelation observed in the RGB stars, the higher is the maximum temperature reached by the bluest HB stars in the GC. This result provides a clear, empirical evidence of a link between the extension of the HB and the presence of star-to-star abundance variations of proton-capture elements in GC stars. We discuss the possible interpretation of this correlation.