Figure: Measured lithium abundances for targets on the main sequence/sub-giant branch as a function of the effective temperature (upper panel) and the sodium content (lower panel). For more details see Monaco et al. 2012, A&A, 539A, 157M.

Abstract: The study of the light element lithium offers clues to the understanding of different problems in astrophysics, ranging from cosmology to the stellar evolution theory. Globular clusters are among the the oldest objects in the Universe and the study of their lithium content may provide insights into the physical conditions during the big bang nucleosynthesis (BBN) phase. In particular, they can help understand the so called "cosmological lithium problem", i.e. the discrepancy between the constant lithium abundance measured in warm metal poor halo stars and the prediction of the standard BBN theory coupled with the the baryonic density measured by the WMAP and the Plank satellites. I will present the results of the spectroscopic investigation on the lithium content among unevolved stars in the globular clusters WCen and M4 and among giant stars in M54.