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 lowmass 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 ω Centauri), which exhibit notably different s-process and/or C+N+O abundance patterns.
D'Orazi, V., Lugaro, M., Angelou, G., Lucatello, S., Gratton, R.g., Bragaglia, A., et al. (2013). A different view on light element anti-correlations in globular clusters: Fluorine abundances in NGC 6656 (M22). MEMORIE DELLA SOCIETÀ ASTRONOMICA ITALIANA, 84(34), 34-37.
A different view on light element anti-correlations in globular clusters: Fluorine abundances in NGC 6656 (M22)
D'Orazi, V.
;
2013-01-01
Abstract
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 lowmass 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 ω Centauri), which exhibit notably different s-process and/or C+N+O abundance patterns.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
