  We have used UVES on VLT-UT2 to take spectra of 15 individual red giant stars
in the centers of four nearby dwarf spheroidal galaxies: Sculptor, Fornax,
Carina and Leo I. We measure the abundance variations of numerous elements in
these low mass stars with a range of ages (1-15Gyr old). This means that we can
effectively measure the chemical evolution of these galaxies WITH TIME. Our
results show a significant spread in metallicity with age, but an overall trend
consistent with what might be expected from a closed (or perhaps leaky) box
chemical evolution scenario over the last 10-15Gyr. We notice that each of
these galaxies show broadly similar abundance patterns for all elements
measured. This suggests a fairly uniform progression of chemical evolution with
time, despite quite a large range of star formation histories. It seems likely
that these galaxies had similar initial conditions, and evolve in a similar
manner with star formation occurring at a uniformly low rate, even if at
different times. With our accurate measurements we find evidence for small
variations in abundances which are correlated to variations in star formation
histories. The alpha-elements suggest that dSph chemical evolution has not been
affected by very high mass stars (>15-20 Msun). The abundance patterns we
measure for stars in dwarf spheroidal galaxies are significantly different from
those typically observed in the disk, bulge and inner-halo of our Galaxy. This
suggests that it is NOT possible to construct a significant fraction of our
Galaxy from STARS formed in these dwarf spheroidal galaxies which subsequently
merged into our own. Any merger scenario involving dSph has to occur in the
very early Universe whilst they are still gas rich, so the majority of mass
transfer is gas, and few stars.
