Estimation of MG/FE Ratio in Early-Type Galaxies [chapter]

B. Barbuy, J. A. De Freitas Pacheco, T. Idiart
1996 New Light on Galaxy Evolution  
Through computed synthetic spectra for individual stars in the Mg2 index region where different values of [Mg/Fe] were considered, and observed features Fe5270 and Fe5335 in a sample of 80 stars, we derived relations Mg 2 and = f(T e //, log g, [Fe/H], [Mg/Fe]). These relations were used to compute integrated indices for single aged populations, where number counts in colour-magnitude diagrams were used. A multi-population model was then built through a convolution of the single stellar
more » ... gle stellar population indices with a metallicity and luminosity distribution for elliptical galaxies, where a chemical evolution model includes enrichment by type II and I supernovae. A grid of 80 multi-population models was computed, by varying the efficiency of star formation rate. In Figure 1 are shown the results for [Mg/Fe] = 0.0, 0.3 and 0.6 compared to observational data by Worthey et al. (1992). An average value of [Mg/Fe] = 0.3 is found for the sample ellipticals. Worthey, G. Faber, S.M., Gonzalez, J.J.: 1992, ApJ, 398, 69 Figure 1. Mg2 vs derived for multi-population models computed with [Mg/Fe] = 0.0, 0.3, 0.6 (solid lines) and sample galaxies by Worthey et al. (filled circles) available at https://doi.
doi:10.1007/978-94-009-0229-9_52 fatcat:qke5f2rzv5efpn6ortfvlhtdnu