The updated BaSTI stellar evolution models and isochrones.IV. alpha-depleted calculations

Abstract

This is the fourth paper of our new release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the updated solar-scaled, alpha-enhanced, and white dwarf model libraries, we present here alpha-depleted ([alpha/Fe] = -0.2) evolutionary tracks and isochrones, suitable to study the alpha-depleted stars discovered in Local Group dwarf galaxies and in the Milky Way. These calculations include all improvements and updates of the solar-scaled and alpha-enhanced models, and span a mass range between 0.1 and 15 Msun, 21 metallicities between [Fe/H] = -3.20 and +0.45 with a helium-to-metal enrichment ratio dY/dZ = 1.31, homogeneous with the solar-scaled and alpha-enhanced models. The isochrones -- available in several photometric filters -- cover an age range between 20 Myr and 14.5 Gyr, including the pre-main-sequence phase. We have compared our isochrones with independent calculations of alpha-depleted stellar models, available for the same alpha-element depletion adopted in present investigation. We have also discussed the effect of an alpha-depleted heavy element distribution on the bolometric corrections in different wavelength regimes. Our alpha-depleted evolutionary tracks and isochrones are publicly available at the BaSTI website.