We combine a number of recent studies of the extended main sequence turn-off ( eMSTO ) phenomenon in intermediate age stellar ( 1 - 2 Gyr ) clusters in the Large Magellanic Cloud ( LMC ) in order to investigate its origin .
By employing the largest sample of eMSTO LMC clusters so far used , we show that cluster core radii , masses , and dynamical state are not related to the genesis of eMSTOs .
Indeed , clusters in our sample have core radii , masses and age-relaxation time ratios in the range \approx 2–6 pc , 3.35– 5.50 ( log ( M _ { cls } / M _ { \odot } ) and 0.2–8.0 , respectively .
These results imply that the eMSTO phenomenon is not caused by actual age spreads within the clusters .
Furthermore , we confirm from a larger cluster sample recent results including young eMSTO LMC clusters , that the FWHM at the MSTOs correlates most strongly with cluster age , suggesting that a stellar evolutionary effect is the underlying cause .