A LARGE STELLAR EVOLUTION DATABASE FOR POPULATION SYNTHESIS STUDIES. V. STELLAR MODELS AND ISOCHRONES WITH CNONa ABUNDANCE ANTICORRELATIONS

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 α-enhanced calculations, and discuss briefly implications for color–magnitude diagrams 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 Strömgren system, or broadband filters blueward of the Johnson V band.