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There are still many open questions on galaxy formation and evolution,
such as e.g. the
predominance of hierarchical or monolithic processes in the galaxy
formation or the temporal evolution of disk metallicity gradients.
Chemical evolution models are generally able to reproduce the present-
time aspect of galaxies in
terms of e.g. average metallicity and radial gradient, gas and star
distribution.
However little is know about the past metal content and star formation
history (SFH) of galaxies.
Chemical abundances of stellar populations of different ages are
essential to constrain the past history of nearby galaxies, both in
terms
of their past metal contents and of SFHs.
In particular, emission-line populations as planetary nebulae (PNe)
and HII regions, have similar spectroscopy
instead of a very different evolutionary stage. Through optical
spectroscopy of these objects we can obtain the elemental
abundances of the same elements and thus put constraints on the
metallicity at different epochs from the galaxy formation.
By means of detailed metallicity studies of nearby galaxies, as M33,
M81, IC10, NGC147, I am trying
to interpret their evolution in terms of their age-metallicity
relationship, of their spatial distribution of chemical abundances at
different epochs,
together with a continuous comparison with chemical evolution models.