Vol. 601
In section 5. Galactic structure, stellar clusters and populations

The Gaia-ESO Survey: the present-day radial metallicity distribution of the Galactic disc probed by pre-main-sequence clusters

This paper presents the first investigation of the present-day radial metallicity distribution of the Galactic disc using [Fe/H] measurements of late type members of 12 pre-main-sequence clusters coming from the Gaia-ESO survey. These measurements cover Galactocentric distances from 6.67 to 8.70 kpc. The radial metallicity distribution is found to be almost flat. The youngest associations have a slightly sub-solar metallicity, and the innermost clusters are found to have [Fe/H] values that are 0.10-0.15 dex more metal poor than the majority of the older clusters at similar Galactocentric radii. The radial metallicity distribution in the Galactic thin disk represents a crucial constraint for modeling disk formation and evolution. These results thus favour models that predict a flattening of the radial gradient over time. However, the decrease in [Fe/H] at young ages is not easily explained by the models. These results reveal a complex interplay of several processes, including star-formation activity, initial mass function, supernova yields, and gas flows that must control the recent evolution of the Milky Way.