ner_tags: O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: overall He spread in 47Tuc is small, a small population of extreme chemistry stars may exist, which is also supported by the fact that only a handful of stars with such strong oxygen depletion has been found by e.g. Cordero et al. (2014) . The AGB polluters in Ventura et al. (2014) are in a mass range where the stars experience a mild Hot Bottom Burning, which is where the Mg-Al burning chain is activated. Their models predict an enhancement of the AGB surface abundances of Al of up to +0.5 dex, whereas the overall Mg abundances are only barely touched, with a depletion of at most 0.04 dex. Considering that the pure AGB ejecta need to be diluted with gas of pristine composition, no detectable variation in the Mg abundance is expected, consistent with our results. On the other hand, one would expect a small variation in [Al/Fe] in the polluted stars, which has indeed been reported by both Carretta et al. (2013) and Cordero et al. (2014) . That we do not see any statistically significant variation in [Al/Fe] in our sample of stars is likely a consequence of our small sample size, as discussed in Paper I. In Fig. 19 , we show the dilution curve for Mg/Mg vs. Mg/Mg, using the same AGB models as in Ventura et al. (2014) . The amount of AGB material increases from left to right in the plot, with the leftmost point giving the pristine composition assumed in their models. Clearly, the bulk of our measured isotopic ratios fall well below the predicted value, even when considering a composition of purely pristine material. However, if one started from a composition with a lower abundance of heavy Mg isotopes, the curve would shift to the left, and show much better agreement with the observations. We note here that the pristine composition assumed by Ventura et al. (2014) starts out with a higher initial fraction of the heavy Mg isotopes, which would explain this offset. During the burning chain that creates the Al enhancement in AGB stars, production of primarily Mg, but also Mg is occurring, and one would thus expect a change in the isotopic distribution between the pristine and polluted populations. Indeed, the AGB models of Ventura et al. (2014) predict a strong decrease of Mg whereas Mg should increase by almost an order of magnitude. Thus, one would expect the Mg abundances to correlate with [Al/Fe] for the polluted population. As discussed earlier, our analysis does not give any indication of such a correlation being present. This is further illustrated in Fig. 20 , where we plot the dilution curve (solid line) for the Mg isotopic fraction vs. [Al/Fe], using the models of Ventura et al. (2014) . The maximum allowed fraction of AGB material is 0.3, as imposed by the constraints from the He abundance variation measured from the extent of the Horizontal Branch in the cluster. Whereas our [Al/Fe] values are within the model prediction, we see no evidence for a strong increase in Mg. Thus, our observations are somewhat in disagreement with the