Lehnert, M. D. and Bell, R. A. and Cohen, J. G. (1991) Abundances in the red giants of M13 and M22. Astrophysical Journal, 367 . pp. 514-523. ISSN 0004-637X. doi:10.1086/169648. https://resolver.caltech.edu/CaltechAUTHORS:20190603-153224354
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Abstract
Abundances of Ca, Na, and Fe are derived for 10 red giant branch stars in the globular clusters M13 and M22, by means of model atmosphere analyses of high-dispersion spectra. It was found that M13 and M22 represent two different types of globular clusters. M13 is similar to M92 and many other globular clusters in that it displays variations in CH and CN band strengths, while showing no variation in either Ca or Fe abundance. The Na abundance was found to vary and its variation correlates with CN band strengths. This suggests that the source of the observed CN band strength variation is the same as that of the Na variation. M22, on the other hand, is similar to ω Cen, in that it displays variations in Ca, Na, and Fe abundances (Δ[Fe/H] ~ Δ[Ca/H] ~ 0.4) and these variations correlate with variations in CH and CN band strengths. These correlations suggest that the cause of the variations in M22 is largely “primordial” and mixing may only make a relatively small contribution to the C and N variations observed.
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| Additional Information: | © American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1990 March 28; accepted 1990 July 26. M. L. would like to thank Jerry Bonnell, Bengt Edvardsson, Mike Briley, and Mike Tripicco for useful discussions and Bengt Gustafsson for his invaluable comments and suggestions on an early version of this paper. This work is supported in part by NSF grant AST85-19570 and AST89-18461 to R. A. B. | |||||||||
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| Subject Keywords: | clusters: globular — stars: abundances | |||||||||
| DOI: | 10.1086/169648 | |||||||||
| Record Number: | CaltechAUTHORS:20190603-153224354 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20190603-153224354 | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 96079 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | George Porter | |||||||||
| Deposited On: | 04 Jun 2019 20:38 | |||||||||
| Last Modified: | 16 Nov 2021 17:17 |
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