A large stellar evolution database for population synthesis studies. V. Stellar models and isochrones with CNONa abundance anticorrelations

TL;DR

This paper introduces a comprehensive grid of stellar models and isochrones that incorporate CNONa abundance anticorrelations observed in globular clusters, aiding the interpretation of complex stellar populations.

Contribution

It provides new stellar models with CNONa abundance patterns, extending previous alpha-enhanced models, and analyzes their impact on stellar evolution and color-magnitude diagrams.

Findings

CNONa abundance patterns affect stellar evolutionary tracks

Models show differences in CMD features like multiple main sequences

Highlights the importance of appropriate color transformations for observations

Abstract

We present a new grid of stellar models and isochrones for old stellar populations, covering a large range of [Fe/H] values, for an heavy element mixture characterized by CNONa abundance anticorrelations as observed in Galactic globular cluster stars. The effect of this metal abundance pattern on the evolutionary properties of low mass stars, from the main sequence to the horizontal branch phase is analyzed. We perform comparisons between these new models, and our reference alpha-enhanced calculations, and discuss briefly implications for CMDs showing multiple main sequence or subgiant branches. A brief qualitative discussion of the effect of CN abundances on color-T_{eff} transformations is also presented, highlighting the need to determine theoretical color transformations for the appropriate metal mixture, if one wants to interpret observations in the Stroemgren system, or broadband filters blueward of the Johnson V-band.