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Accueil > Séminaires > The Lithium content of globular (…)

The Lithium content of globular clusters and in giant stars

Lorenzo Monaco (ESO)

Globular clusters (GCs) are among the oldest objects in the
universe. By studying their Li content, insights can be gained about
both the cosmological Lithium problem — namely the discrepancy between
the Li abundance predicted by standard big bang nucleosynthesis coupled
with the baryonic density measured by WMAP and the constant value
observed in warm metal poor halo stars, i.e. the Spite plateau — and
about the ubiquitous multi-population identified in GCs and, hence,
about their chemical enrichment history.
I will present the results of two spectroscopic campaigns aimed at studying the Li content of unevolved stars in the GCs ωCen and M4. Additionally, I will also present the results of a search for Li-rich giants among thick disk
stars and stars belonging to the Sagittarius dwarf spheroidal galaxy
tidal streams. An overall dilution of the stellar lithium content
happens as soon as a star evolve off the main sequence. Nevertheless, a
few percent of giant stars present high lithium abundances, whose origin
is not yet completely understood, at least for low mass stars.