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Fig. 2


Diagram of (b, cy) for AGB and RGB stars of NGC 6752 (left). The typical photometric errors are indicated by the error bars on the left of the diagram. The upper right panel compares the sodium-oxygen anti-correlation for RGB stars (bullets) and AGB stars (triangles) from Yong et al. (2013) and Lapenna et al. (2016). The dashed line separates population A and B AGB stars, which are coloured green and purple, respectively. The same colours are used to represent these AGB stars in the other panels of this figure. The lower right panel shows [Na/Fe] as a function of the stellar effective temperature for RGB (diamonds) and AGB stars (triangles) from Campbell et al. (2013). The dashed line separates the two groups first and second population stars defined by Campbell and collaborators, which are coloured red and blue, respectively. RGB stars with [Na/Fe] > 0.5 are denoted with yellow dots. These symbols and colours are used to represent the same RGB stars in the diagram in the left panel.

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