Campbell, Simon WD’Orazi , VYong, DavidConstantino, Thomas NLattanzio, JohnStancliffe, RichardAngelou, G CWylie de Boer, ElizabethGrundahl, Frank2015-12-130028-0836http://hdl.handle.net/1885/73011The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars, they still provide relatively homogeneous samples of starsKeywords: sodium; cosmology; evolutionary theory; sodium; spectroscopy; timescale; article; asymptotic giant branch; chemical analysis; conceptual framework; cosmological phenomena; evolution; mathematical analysis; measurement; predictive value; priority journal;201310.1038/nature121912016-02-24