The r-Process Enriched Halo Star CS22892-052

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Session 22 -- Stellar Spectroscopy, Atmospheres, Models, Intrinsic Variables, Theory, Part II
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

[22.03] The r-Process Enriched Halo Star CS22892-052

C. Sneden (U. Texas), A. McWilliam, G. W. Preston (Carnegie Obs.), J. J. Cowan (U. Oklahoma)

New high resolution, high S/N spectra have been obtained for the halo K-giant star CS 22892-052. Our previous analysis of a high resolution but low S/N spectrum of this star showed that it has a very low metallicity ([Fe/H] $\sim$ -3), and that the abundance pattern for nearly all elements with Z$<$30 is normal for a metal-poor star. But the elements with Z$>$30 are all very overabundant with respect to iron. The overabundances of the heaviest elements rise with increasing Z, indicating their creation in an r-process neutron capture nucleosynthesis environment. With our new spectra of CS 22892-052 we derive the most complete neutron capture element abundance set of any very metal-poor star. This new abundance set includes the seldom-observed rare earth elements erbium and ytterbium, and the first abundance determination of holmium in a metal-poor star. Thorium is cleanly detected in the CS 22892-052 spectrum. Abundance upper limits are derived for additional elements of nucleosynthesis interest. The observed abundance pattern is compared to the predictions of supernova r-process nucleosynthesis, and a galactic halo age estimate is derived from the thorium abundance.

This work was partially supported with funds from NSF grant AST 93-15068.

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