Release 11.12 ("Hergest Ridge")


Gclusters :: Bibliographic item "gc504"

Article ID: gc504
AuthorCarretta, Eugenio
TitleFive Groups of Red Giants with Distinct Chemical Composition in the Globular Cluster NGC 2808
JournalThe Astrophysical Journal, Volume 810, Issue 2, article id. 148, 17 pp.
Year of publication2015 (on gclusters from 2015-12-03 16:17:41 )
AbstractThe chemical composition of multiple populations in the massive globular cluster (GC) NGC 2808 is addressed with the homogeneous abundance reanalysis of 140 red giant branch stars. UVES spectra for 31 stars and GIRAFFE spectra for the other giants were analyzed with the same procedures used for about 2500 giants in 23 GCs in our FLAMES survey, deriving abundances of Fe, O, Na, Mg, Si, Ca, Ti, Sc, Cr, Mn, and Ni (...) About 14% of our sample is formed by giants with solar or subsolar [Mg/Fe] ratios. Using the [Na/Mg] ratios, we confirm the presence of five populations with different chemical compositions that we call P1, P2, I1, I2, and E in order of decreasing Mg and increasing Na abundances. Statistical tests show that the mean ratios in any pair of groups cannot be extracted from the same parent distribution. The overlap with the five populations recently detected from UV photometry is good but not perfect, confirming that more distinct components probably exist in this complex GC.
Also available at:http://arxiv.org/abs/1507.07553
TagsNGC 2808

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