  The atmospheres and winds of C-type AGB stars are modeled with the 1D
spherically symmetric radiation-hydrodynamical code DARWIN. To explore the
metallicity-dependence of mass loss we calculate model grids at three different
chemical abundances. Since carbon may be dredged up during the thermal pulses
as AGB stars evolve, we keep the carbon abundance as a free parameter. The
models in these three different grids all have a current mass of one solar
mass; effective temperatures of 2600K, 2800K, 3000K, or 3200K; and stellar
luminosities equal to log(L/Lsun)=3.70, 3.85, or 4.00.
  The models show that mass loss in carbon stars is facilitated by high
luminosities, low effective temperatures, and a high carbon excess (C-O) at
both solar and subsolar metallicities. Similar combinations of effective
temperature, luminosity, and carbon excess produce outflows at both solar and
subsolar metallicities. There are no large systematic differences in the
mass-loss rates and wind velocities produced by these wind models with respect
to metallicity, nor any systematic difference concerning the distribution of
grain sizes or how much carbon is condensed into dust. DARWIN models at
subsolar metallicity have approximately 15% lower mass-loss rates compared to
DARWIN models at solar metallicity with the same stellar parameters and carbon
excess. For both solar and subsolar environments typical grain sizes range
between 0.1 and 0.5 micron, the degree of condensed carbon varies between 5%
and 40%, and the gas-to-dust ratios between 500 and 10000. Furthermore, stellar
evolution models can use the mass-loss rates calculated from DARWIN models at
solar metallicity when modeling the AGB phase at subsolar metallicities if
carbon excess is used as the critical abundance parameter instead of the C/O
ratio.
