GES iDR4 Mg-Al anticorrelation in GCs

The results compare well with the available literature, within 0.1~[-] or less, after a small (compared to the Minternal spreads) offset between the UVES and the GIRAFFE data of 0.10-0.15dex was taken into account. In particular, we present for the first time data for NGC 5927, one of the most metal-rich globular clusters studied in the literature so far with [Fe/H]=-0.49dex, that was included to connect with the open cluster regime in the Gaia-ESO Survey internal calibration.

The extent and shape of the Mg-Al anti-correlation provide strong constraints on the multiple population phenomenon in globular clusters. In particular, we studied the dependency of the Mg-Al anti-correlation extension with metallicity, present-day mass, and age of the clusters, using GES data in combination with a large set of homogenized literature measurements. We find a dependency with both metallicity and mass, that is evident when fitting for the two parameters simultaneously, but no significant dependency with age.