Stellar population analysis of two ellipticals

Abstract

The spatial distributions of the mean luminosity-weighted stellar age, metallicity, and alpha/Fe ratio along both photometric axes of two nearby elliptical galaxies have been obtained using Lick index measurements on long slit spectra in order to reconstruct the star formation history in their kinematically distinct subsystems. Lick indexes were compared with those of single-aged stellar population (SSP) models. A population synthesis method was also applied in order to help disentangling the age-metallicity degeneracy. The stars characteristics are associated with their kinematics: they are older and alpha-enhanced in the not rotating bulge of NGC 1052 and counter rotating core of NGC 7796, while they show a strong spread of alpha/Fe and age along the rotating disk of NGC 1052 and an outwards radial decreasing of them outside the core of NGC 7796.