NOAO >   Observing Info >   Approved Programs >   2004B-0433

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Proposal Information for 2004B-0433


PI: Aaron Steinhauer, University of Florida, aarons@astro.ufl.edu
Address: Department of Astronomy, 211 Bryant Space Science Center, Gainesville, FL 32611-2055, USA

CoI: Constantine Deliyannis, Indiana University

Title: Survey for Super-Lithium-Rich Stars in Nearby Open Clusters

Abstract: The super-Li-rich star J37 remains an enigma. Both microscopic diffusion and planetary accretion have been proposed to explain its extraordinary enhancement of Li by more than a factor of ten. Each scenario successfully predicts observed over- and under-abundances of many other elements, but neither can explain all of the observations. Our own recent preliminary determination of an enhanced Be abundance argues strongly for accretion. Now, four other stars with unusually high Li abundances have been found, raising the question: is this a new class of stars? Further complicating matters, all five stars reside in the very narrow \teff range where diffusion predicts Li-enhancement. However, a mere five stars will not definitively distinguish the relative merits of the diffusion vs. accretion scenario; hence, a larger sample is required. We propose to conduct a survey of twelve nearby clusters to look for additional super-Li-rich stars; we expect to find about six more such stars, which will more than double the current sample. The Li abundances alone (together, perhaps, with the abundances of several other elements that can be derived near the Li line) may lead to key conclusions. For example, if \it all Li-rich stars are found in the narrow Li-peak range, then diffusion \it must at least be a contributor. Subsequent study of the multiple elements in the Li-rich stars may then reveal the cause(s) of the Li-richness and establish whether this is a new class of stars.


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