Browsing by Subject "kinetic equilibrium"

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Manganese Abundances In The Globular Cluster Omega Centauri
(2010-07) Cunha, Katia; Smith, Verne V.; Bergemann, Maria; Suntzeff, Nicholas B.; Lambert, David L.; Lambert, David L.
We present manganese abundances in 10 red giant members of the globular cluster omega Centauri; eight stars are from the most metal-poor population (RGB MP and RGB MInt1) while two targets are members of the more metal-rich groups (RGB MInt2 and MInt3). This is the first time Mn abundances have been studied in this peculiar stellar system. The LTE values of [Mn/Fe] in omega Cen overlap those of Milky Way stars in the metal-poor. Cen populations ([Fe/H] similar to -1.5 to -1.8), however unlike what is observed in Milky Way halo and disk stars, [Mn/Fe] declines in the two more metal-rich RGB MInt2 and MInt3 targets. Non-LTE calculations were carried out in order to derive corrections to the LTE Mn abundances. The non-LTE results for omega Cen in comparison with the non-LTE [Mn/Fe] versus [Fe/H] trend obtained for the Milky Way confirm and strengthen the conclusion that the manganese behavior in omega Cen is distinct. These results suggest that low-metallicity supernovae (with metallicities <= -2) of either Type II or Type Ia dominated the enrichment of the more metal-rich stars in omega Cen. The dominance of low-metallicity stars in the chemical evolution of omega Cen has been noted previously in the s-process elements where enrichment from metal-poor asymptotic giant branch stars is indicated. In addition, copper, which also has metallicity-dependent yields, exhibits lower values of [Cu/Fe] in the RGB MInt2 and MInt3 omega Cen populations.