Osservatorio Astrofisico di Arcetri

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


This paper, by Lorenzo Spina, former PhD student at the Osservatorio di Arcetri and now postdoc in Sao Paulo (Brazil), Sofia Randich, Laura Magrini and collaborators from the Gaia-ESO Survey,  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.

From the A&A highlight page:

Reference: L. Spina, S. Randich, L. Magrini, et al. A&A 601, A70