The light-element variations among globular cluster (GC) stars are nowadays accepted as the signature of self-enrichment from previous generations of stars. It is expected that these extinct progenitors experienced hot H-burning and, as fluorine is involved in the complete CNO cycle, the F abundance in GCs can provide new clues about the previous generation(s). Along with Na-O and Mg-Al anti-correlations, theory predicts an anti-correlation between F and Na and a positive correlation between F and O. Moreover, relatively low-mass AGB stars are F producers (and are also responsible for C+N+O and s-process element variations). We present our results on F abundances in four GCs (NGC 6656, NGC 6752, 47 Tucanae and omega Centauri), which exhibit notably different s-process and/or C+N+O abundance patterns.
|Number of pages||4|
|Journal||Memorie della Societa Astronomica Italiana - Journal of the Italian Astronomical Society|
|Publication status||Published - 2013|
- stars: abundances
- stars: Population II
- galaxy: globular clusters
- stars: AGB and post-AGB