Gravitational and mass distribution effects on stationary superwinds I
  Here, we model the effect of non-uniform dynamical mass distributions and
their associated gravitational fields on the stationary galactic superwind
solution. We do this by considering an analogue injection of mass and energy
from stellar winds and SNe. We give analytical formulae that establish when an
outflow is possible and also characterize distinct flow regimes and enrichment
scenarios. We also constraint the parameter space by giving approximate limits
above which gravitation, self-gravitation and radiative cooling can inhibit the
stationary flow. Later, we obtain analytical expressions for the free superwind
hydrodynamical profiles. We find that the existence or inhibition of the
superwind solution highly depends on the steepness and concentration of the
dynamical mass and the mass and energy injection rates, not just in their
effective total values. We compare our results with observational data and a
recent numerical work that models artificial massive galaxies assuming a
uniform distribution of their parameters. Finally, we put our results in the
context of the mass-metallicity relationship to discuss observational evidence
related to the selective loss of metals from the less massive galaxies and the
recent discovery of high-metallicity dwarf spheroidal (dSph) and dwarf
elliptical (dE) galaxies.
