We use the combination of photometric and spectroscopic data of 47 Tuc stars to reconstruct the possible formation of a second generation of stars in the central regions of the cluster , from matter ejected from massive Asymptotic Giant Branch stars , diluted with pristine gas .

The yields from massive AGB stars with the appropriate metallicity ( Z=0.004 , i.e .
[ Fe/H ] = -0.75 ) are compatible with the observations , in terms of extension and slope of the patterns observed , involving oxygen , nitrogen , sodium and aluminium .

Based on the constraints on the maximum helium of 47 Tuc stars provided by photometric investigations , and on the helium content of the ejecta , we estimate that the gas out of which second generation stars formed was composed of about one-third of gas from intermediate mass stars , with M \geq 5 M _ { \odot } and about two-thirds of pristine gas .
We tentatively identify the few stars whose Na , Al and O abundances resemble the undiluted AGB yields with the small fraction of 47 Tuc stars populating the faint subgiant branch .

From the relative fraction of first and second generation stars currently observed , we estimate that the initial FG population in 47 Tuc was about 7.5 times more massive than the cluster current total mass .