Tagging the Chemical Evolution History of the Large Magellanic Cloud
  Disk
  We have used high-resolution spectra obtained with the multifiber facility
FLAMES at the Very Large Telescope of the European Southern Observatory to
derive kinematic properties and chemical abundances of Fe, O, Mg and Si for 89
stars in the disk of the Large Magellanic Cloud (LMC). The derived metallicity
and [alpha/Fe], obtained as the average of O, Mg and Si abundances, allow us to
draw a preliminary scheme of the star formation history occurred in this region
of the LMC. The derived metallicity distribution shows two main components: one
component (comprising ~ 84% of the sample) is peaked at [Fe/H] = -0.48 dex and
it shows an [alpha/Fe] ratio slightly under solar ([alpha/Fe] ~ -0.1 dex). This
population was probably originated by the main star formation event occurred
3-4 Gyr ago (possibly triggered by tidal capture of the Small Magellanic
Cloud). The other component (comprising ~ 16% of the sample) is peaked at
[Fe/H] ~ -1 dex and it shows an [alpha/Fe] ~ 0.2 dex. This population was
probably generated during the long quiescent epoch of star formation in between
the first episode and the most recent bursts. Indeed, in our sample we do not
find stars with chemical properties similar to the old LMC globular clusters
nor to the iron-rich and alpha-poor stars recently found in the LMC globular
cluster NGC 1718 and predicted to be also in the LMC field, thus suggesting
that both these components are small (< 1%) in the LMC disk population.
