Energetic constraints to chemo-photometric evolution of spiral galaxies
  The problem of chemo-photometric evolution of late-type galaxies is dealt
with relying on prime physical arguments of energetic self-consistency between
chemical enhancement of galaxy mass, through nuclear processing inside stars,
and luminosity evolution of the system. Chemical enhancement is assessed in
terms of the so-called "yield metallicity", that is the metal abundance of
processed mass inside stars, as constrained by the galaxy photometric history.
