  The results of a spectroscopic and photometric investigation of the central
region of M 31 are presented. An analysis of absorption-index radial profiles
involving magnesium, calcium, and iron lines has shown that the unresolved
nucleus of M 31 is distinct by its increased metallicity; unexpectedly, among
two nuclei of M 31, it is the faintest one located exactly in the dynamical
center of the galaxy (and dynamically decoupled) which is chemically distinct.
The Balmer absorption line H-beta has been included into the analysis to
disentangle metallicity and age effects; an age difference by a factor 3 is
detected between stellar populations of the nucleus and of the bulge, the
nucleus being younger. The morphological analysis of CCD images has revealed
the presence of a nuclear stellar-gaseous disk with a radius of some 100 pc,
the gas component of which looks non-stationary, well inside the bulge of M 31.
