Lost and found: evidence of Second Generation stars along the Asymptotic
  Giant Branch of the globular cluster NGC 6752
  We derived chemical abundances for C, N, O, Na, Mg and Al in 20 asymptotic
giant branch (AGB) stars in the globular cluster NGC 6752. All these elements
(but Mg) show intrinsic star-to-star variations and statistically significant
correlations or anticorrelations analogous to those commonly observed in red
giant stars of globular clusters hosting multiple populations. This
demonstrates that, at odds with previous findings, both first and second
generation stars populate the AGB of NGC 6752. The comparison with the Na
abundances of red giant branch stars in the same cluster reveals that second
generation stars (with mild Na and He enrichment) do reach the AGB phase. The
only objects that are not observed along the AGB of NGC 6752 are stars with
extreme Na enhancement. This is also consistent with standard stellar evolution
models, showing that highly Na and He enriched stars populate the bluest
portion of the horizontal branch and, because of their low stellar masses,
evolve directly to the white dwarf cooling sequence, skipping the AGB phase.
