Recent studies have revealed that the Multiple Populations ( MPs ) phenomenon does not occur only in ancient and massive Galactic globular clusters ( GCs ) , but it is also observed in external galaxies , where GCs sample a wide age range with respect to the Milky Way .
However , for a long time , it was unclear whether we were looking at the same phenomenon in different environments or not .
The first evidence that the MPs phenomenon is the same regardless of cluster age and host galaxy came out recently , when an intermediate-age cluster from the Small Magellanic Cloud , Lindsay 1 , and a Galactic GC have been directly compared .
By complementing those data with new images from the Hubble Space Telescope ( HST ) , we extend the comparison to two clusters of different ages : NGC 2121 ( \sim 2.5Gyr ) and NGC 1783 ( \sim 1.5Gyr ) , from the Large Magellanic Cloud .
We find a clear correlation between the RGB width in the pseudo-colour C _ { F 275 W,F 343 N,F 438 W } and the age of the cluster itself , with the older cluster having larger \sigma ( C _ { F 275 W,F 343 N,F 438 W } ) ^ { RGB } and vice-versa .
Unfortunately , the \sigma values can not be directly linked to the N-abundance variations within the clusters before properly taking account the effect of the first dredge-up .
Such HST data also allow us to explore whether multiple star-formation episodes occurred within NGC 2121 .
The two populations are indistinguishable , with an age difference of only 6 \pm 12 Myr and an initial Helium spread of 0.02 or lower .
This confirms our previous results , putting serious constraints on any model proposed to explain the origin of the chemical anomalies in GCs .