EVIDENCE FOR MERGER SIGNATURES IN THE LINE-STRENGTH GRADIENTS OF ELLIPTIC GALAXIES .1. A UNIVERSAL RELATION BETWEEN METALLICITY AND POTENTIAL DEPTH FOR ALL HOT STELLAR-SYSTEMS .2.

In the first part of this paper it is shown that those giant ellipticals which presumably formed in a violent merging process (as inferred from their peculiar core kinematics) reflect the details of the merging in their Mg2-index profiles. In the second part it is demonstrated that, independent from other structural parameters, central Mg2 index and central velocity dispersion sigma(o) (presumably representing the mean depth of the potential well) follow a unique relationship for all types of hot stellar systems (including diffuse dwarf ellipticals, compact ellipticals, bulges and giant ellipticals).