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arXiv · 0904.3507

A Large Sample Study of Red Giants in the Globular Cluster Omega Centauri (NGC 5139)

Christian I. Johnson·Catherine A. Pilachowski·R. Michael Rich·Jon P. Fulbright
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Abstract

We present abundances of several light, alpha, Fe-peak, and neutron-capture elements for 66 red giant branch (RGB) stars in the Galactic globular cluster Omega Centauri. Our observations lie in the range 12.0 5 M_sun asymptotic giant branch (AGB) stars. At [Fe/H]>-1.2, more than 75% of the stars are Na/Al enhanced and may have formed almost exclusively from AGB ejecta. Most of these stars are enhanced in Na by at least 0.2 dex for a given Al abundance than would be expected based on "normal" globular cluster values. All stars in our sample are alpha-rich and have solar-scaled Fe-peak abundances. Eu does not vary extensively as a function of metallicity; however, [La/Fe] varies from about -0.4 to +2 and stars with [Fe/H]>-1.5 have [La/Eu] values indicating domination by the s-process. A quarter of our sample have [La/Eu]>+1 and may be the result of mass transfer in a binary system.

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Christian I. Johnson, Catherine A. Pilachowski, R. Michael Rich, Jon P. Fulbright. 2009-04-22. A Large Sample Study of Red Giants in the Globular Cluster Omega Centauri (NGC 5139). https://doi.org/10.1088/0004-637x%2F698%2F2%2F2048

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