The two metallicity groups of the globular cluster M 22 : a chemical perspective

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DOIResolve DOI: http://doi.org/10.1051/0004-6361/201116546
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleAstronomy and Astrophysics
ISSN0004-6361
Volume532
Article numberA8
PagesA8-1–; # of pages: 24
Subjecttechniques: spectroscopic; stars: abundances; stars: Population II; globular clusters: individual: M 22 (NGC 6656)
AbstractWe present a detailed chemical composition analysis of 35 red giant stars in the globular cluster M 22. High resolution spectra for this study were obtained at five observatories, and analyzed in a uniform manner. We have determined abundances of representative light proton-capture, α, Fe-peak and neutron-capture element groups. Our aim is to better understand the peculiar chemical enrichment history of this cluster, in which two stellar groups are characterized by a different content in iron, neutron capture elements Y, Zr and Ba, and α element Ca. The principal results of this study are: (i) substantial star-to-star metallicity scatter (- 2.0 ≲ [Fe/H] ≲ -1.6); (ii) enhancement of s-process/r-process neutron-capture abundance ratios in a fraction of giants, positively correlated with metallicity; (iii) sharp separation between the s-process-rich and s-process-poor groups by [La/Eu] ratio; (iv) possible increase of [Cu/Fe] ratios with increasing [Fe/H], suggesting that this element also has a significant s-process component; and (v)presence of Na-O and C-N anticorrelations in both the stellar groups.
Publication date
PublisherEDP Sciences
LanguageEnglish
AffiliationNRC Herzberg Institute of Astrophysics; National Research Council Canada
Peer reviewedYes
NPARC number19669788
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Record identifier3df02aa7-3f5f-437b-92f9-6a87b099c190
Record created2012-03-16
Record modified2016-05-09
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