Sodium abundances of AGB and RGB stars in Galactic globular clusters II. Analysis and results of NGC 104, NGC 6121 and NGC 6809

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We analyzed the high-resolution spectra of a large sample of AGB and RGB stars in the Galactic globular clusters (GCs) NGC 104, NGC 6121, and NGC 6809 obtained with FLAMES/GIRAFFE at ESO/VLT, and determined their Na abundances.

• This is the first time that the AGB stars in NGC 6809 are targeted.
• Moreover, we reanalyzed with the same method the data archive for NGC 6752.
• To investigate the dependence of AGB Na abundance dispersion on GC parameters, we compared the AGB [Na/H] distributions we obtained (including NGC 2808 presented in the first paper of this series) with literature data for four other GCs, i.e., a total of nine GCs, covering a wide range of GC parameters.