AAS 203rd Meeting, January 2004
Session 85 Stellar Structure, Evolution and Abundances
Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Grand Hall

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[85.08] Germanium, Osmium, and Platinum in Low Metallicity Halo Giants

C. Sneden, J. J. Cowan, T. C. Beers, F. Primas, J. W. Truran, S. Burles ()

We present elemental abundances (and/or) upper limits for the neutron-capture elements germanium (Z=32), osmium (76), and platinum (78) for a dozen low metallicity ([Fe/H]~<~--1.5) halo field giants. These abundances are compared with previously-determined results for lanthanum (57) and europium (63) for the same stars.

The abundances of Os and Pt are well correlated with those of La and Eu, but the Ge abundances do not scale with those of the heavier neutron-capture elements, and in fact appear to better track the Fe-peak abundances in these stars. Rapid neutron-capture synthesis (i.e. the r-process) is responsible for the creation of the heaviest (Z~\geq~56) neutron-capture elements in these low-metallicity stars. The nucleosynthesis puzzle now is to understand the formation of Ge and its neighbors in the Periodic Table.

This research has been supported by grants from the Hubble Space Telescope (STScI grant GO-08342), and the NSF grants AST-0307495, AST-0098508, AST-0098549, and AST-0307279.

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