The Mg/Fe characterization of the MILES library for stellar populations studies

TL;DR

This paper provides [Mg/Fe] abundance ratios for most stars in the MILES library, enabling the development of more accurate stellar population models with alpha-enhancement for ages over 1 Gyr.

Contribution

It introduces a uniform calibration of [Mg/Fe] for MILES stars, combining high and medium resolution data to improve stellar population synthesis models.

Findings

[Mg/Fe] ratios obtained for 77% of MILES stars

Uncertainties of 0.06 and 0.12 dex for high and medium resolution data

Enables semi-empirical alpha-enhanced SSP models for ages > 1 Gyr

Abstract

We have obtained [Mg/Fe] for around 77% of the stars of the MILES library of stellar spectra in order to include this important information into simple stellar population (SSP) models. The abundance ratios, which were carefully calibrated to a single uniform scale, were obtained through a compilation from high spectral resolution works plus robust spectroscopic analysis at medium resolution. The high resolution data provided an extensive control sample. Average uncertainties (0.06 and 0.12 dex for the high and medium resolution samples respectively) and the good coverage of the stars with [Mg/Fe] over the MILES's parameter space will permit us to semi-empirically build up new SSP models with accurate alpha-enhancements for ages older than 1 Gyr. This will open new prospects for evolutionary stellar population synthesis.