On the Galactic globular cluster Delta VHBbump parameter .

Di Cecco, A.; Bono, G.; Pietrinferni, A.; Becucci, R.; Stetson, P. B.; Cassisi, S.; Degl'Innocenti, S.; Prada Moroni, P.; Monelli, M.; Buonanno, R.; Corsi, C. E.; Caputo, F.; Iannicola, G.; Ferraro, I.; Pulone, L.; Walker, A. R.
Bibliographical reference

Memorie della Società Astronomica Italiana Supplement, v.14, p.103 (2010)

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2010
Number of authors
16
IAC number of authors
0
Citations
0
Refereed citations
0
Description
We calculated new estimates of the Delta VHBbump parameter for 15 Galactic Globular Clusters (GGCs) using accurate ground-based photometric data. We enlarged our sample with literature data and we obtained a sample of 62 GGCs covering a wide metallicity range (-2.16le [M/H]le -0.58 dex). To compare the data with the theory we used theoretical models from citet{pie04} and two different metallicity scales. We found that the observed values are higher (˜0.4 mag) than the canonical predictions. Moreover, the discepancy increases in the citet{ki03} metallicity scale and it decreases in the citet{cg97} scale. We investigated also the impact of CNONa extreme mixture and higher He-enhanced abundance (Y=0.30). The use of these models is not in the direction to explain the observed discrepancy.