The Gaia -ESO Survey: Lithium enrichment histories of the Galactic thick
  and thin disc
  Lithium abundance in most of the warm metal-poor main sequence stars shows a
constant plateau (A(Li)~2.2 dex) and then the upper envelope of the lithium vs.
metallicity distribution increases as we approach solar metallicity.
Meteorites, which carry information about the chemical composition of the
interstellar medium at the solar system formation time, show a lithium
abundance A(Li)~3.26 dex. This pattern reflects the Li enrichment history of
the interstellar medium during the Galaxy lifetime. After the initial Li
production in Big Bang Nucleosynthesis, the sources of the enrichment include
AGB stars, low-mass red giants, novae, type II supernovae, and Galactic cosmic
rays. The total amount of enriched Li is sensitive to the relative contribution
of these sources. Thus different Li enrichment histories are expected in the
Galactic thick and thin disc. We investigate the main sequence stars observed
with UVES in Gaia-ESO Survey iDR4 catalog and find a Li-[alpha/Fe]
anticorrelation independent of [Fe/H], Teff, and log(g). Since in stellar
evolution different {\alpha} enhancements at the same metallicity do not lead
to a measurable Li abundance change, the anticorrelation indicates that more Li
is produced during the Galactic thin disc phase than during the Galactic thick
disc phase. We also find a correlation between the abundance of Li and
s-process elements Ba and Y, and they both decrease above the solar
metallicity, which can be explained in the framework of the adopted Galactic
chemical evolution models.
