  This study is an attempt to determine the metallicities of WUMa-type binary
stars using spectroscopy. ~4,500 spectra collected at the David Dunlap
Observatory were subject to the same Broadening Function processing to
determine the combined line strength in the spectral window centered on the MgI
triplet (5080-5285A). Individual integrated BF's were phase averaged to derive
a single line-strength indicator. The sample was limited to 90 EW binaries with
the strict phase-constancy of colors and without spectral contamination by
companions. The best defined results were obtained for a F-type sub-sample
(0.32<(B-V)0<0.62) of 52 stars for which the BF strengths could be interpolated
in the model predictions. The metallicities, [M/H], for the F-type sub-sample
indicate abundances roughly similar to the solar [M/H], but with a large
scatter which is partly due to combined random and systematic errors. Because
of a color trend resulting from limitations in our approach, we set the scale
of metallicities to correspond to that derived from the m_1 index of the
Stromgren photometry for F-type binaries. The trend-adjusted [M/H]1 are
distributed within -0.65<[M/H]1<+0.50, with the spread reflecting genuine
metallicity differences between stars. One half of the F-sub-sample binaries
have [M/H]1 within -0.37<[M/H]1 +0.10, a median of -0.04 and a mean of -0.10,
with a tail towards low metallicities, and a possible bias against very high
metallicities. A parallel study of kinematic data, utilizing the most reliable
and recently obtained proper motion and radial velocity data for 78 stars of
the full sample, shows that the F-type sub-sample binaries have similar
kinematic properties to solar neighborhood, thin-disk dwarfs with ages about 3
- 5.5 Gyr. The F-type binaries which appear to be older than the rest tend to
have systematically smaller mass-ratios than most of the EW binaries of the
same period.
