Spectroscopic Gradients in Elliptical Galaxies

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Preliminary results based on a large compilation of line-strength profiles are presented and discussed. Elliptical galaxies (Es) with strong central Mg₂ show steeper line-strength gradients. These galaxies are more massive and have higher velocity dispersions, note nevertheless, that the Mg₂ gradient correlates better with central Mg₂ than with any other global or structural parameter. This correlation, and the fact that Mg₂ measures Z/Z together with the [Mg/Fe] abundances among Es, are of extreme importance for the use of the central Mg₂-σ relation as a reflection of a mass-metallicity relation. Spectroscopic gradients arise mainly from a radial decrease in mean stellar metallicity. However, the Mg₂ and < Fe> gradients do not correlate within measuring errors, indicating that something else, besides metallicity, is also varying within a galaxy. Hβ gradients indicate that the centers of Es tend to look spectroscopically ``younger'' than their stellar populations further out.