METAL ENRICHMENT IN ELLIPTIC GALAXIES AND GLOBULAR-CLUSTERS THROUGH THE STUDY OF IRON AND H-BETA SPECTRAL INDEXES

Chemical evolution of elliptical galaxies and globular clusters is add ressed through a combined study of the iron indices at 5270 and 5335 A ngstrom and of the H beta line strength. The observational database of 74 standard stars (both dwarfs and giants) referred to in a previous paper {Buzzoni et al. [AJ, 103, 1814, (1992)]} complemented with the d ata of Faber et al. [ApJS, 57, 711 (1985)] and Gorgas et al. [ApJS, 86 , 153 (1993)] allowed us to explore here Fe and H beta index dependenc e on stellar temperature, gravity, and metallicity. The derived fittin g functions were then included into Buzzoni's [ApJS, 71, 817 (1989)] c ode for population synthesis in order to derive expected integrated in dices for simple stellar populations and compare with observations. Pa rtition of metals in the,current chemical mix of galaxies and globular s has been constrained supporting the claim that light alpha elements might be enhanced in the globular cluster metal-poor population. An al ternative conclusion resting on the standard framework with [alpha/Fe] =0 would require a systematically larger age, about 18-20 Gyr. Iron an d magnesium in ellipticals are found in average solar but a systematic trend of [Mg/Fe] vs global metallicity does exist with iron more defi cient with respect to magnesium at high Z. We conclude that this effec t might indicate that Fe abundance per unit mass in the galaxies is co nstant (suggesting a constant rate per unit mass of SN I events) while light metals supplied by SNe II should have been more effectively enr iched with increasing galactic total mass.