The chemical characterisation of young stars

The determination of the detailed chemical composition of stars is critical in many astrophysical fields, including (but not limited to) the characterisation of planetary systems. Previous studies seem to indicate an anomalous chemical pattern of the young(est) stellar populations in the solar vicinity. The chemical peculiarities include sub-solar [Fe/H] ratios, over-abundances of ionised atoms, and the Ba puzzle. Our investigation suggests that these effects are related to abundance analysis techniques, which have important limitations when applied to young stars. The main role is played by the intense stellar activity, although a comprehensive understanding of this complex behaviour is still wanting. It shapes the spectral lines, altering the derivation of the stellar parameters (and also the chemical abundances) when derived in a standard way. For these reasons, new spectroscopic techniques are needed especially to analyse young stars