The wind speeds, dust content, and mass-loss rates of evolved AGB and
  RSG stars at varying metallicity
  We present the results of our survey of 1612 MHz circumstellar OH maser
emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in
the Large Magellanic Cloud. We have discovered four new circumstellar maser
sources in the LMC, and increased the number of reliable wind speeds from IR
stars in the LMC from 5 to 13. Using our new wind speeds, as well as those from
Galactic sources, we have derived an updated relation for dust driven winds:
$v_{exp} \propto Z L^{0.4}$. We compare the sub-solar metallicity LMC OH/IR
stars with carefully selected samples of more metal-rich OH/IR stars, also at
known distances, in the Galactic Centre and Galactic Bulge. For 8 of the Bulge
stars we derive pulsation periods for the first time, using near-IR photometry
from the VVV survey. We have modeled our LMC OH/IR stars and developed an
empirical method of deriving gas-to-dust ratios and mass loss rates by scaling
the models to the results from maser profiles. We have done this also for
samples in the Galactic Centre and Bulge and derived a new mass loss
prescription that includes luminosity, pulsation period, and gas-to-dust ratio
$\dot{M} = 1.06^{+3.5}_{-0.8} \rm{ \cdot
}10^{-5}\,(L/10^4\,\rm{L}_\odot)^{0.9\pm0.1}(P/500\,\rm{d})^{0.75\pm0.3}
(r_{gd}/200)^{-0.03\pm0.07}\,\rm{M_{\odot}}\, yr^{-1}$. The tightest
correlation is found between mass loss rate and luminosity. We find that the
gas-to-dust ratio has little effect on the mass loss of oxygen-rich AGB stars
and RSGs within the Galaxy and the LMC. This suggests that mass loss of
oxygen-rich AGB stars and RSGs is (nearly) independent of metallicity between a
half and twice solar.
