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New Keck observations of lithium in very metal-poor stars

Published online by Cambridge University Press:  23 December 2005

Ann Merchant Boesgaard
Affiliation:
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 USA email: boes@ifa.hawaii.edu, mnovicki@ifa.hawaii.edu, Alex_C_Stephens@yahoo.com
Megan C. Novicki
Affiliation:
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 USA email: boes@ifa.hawaii.edu, mnovicki@ifa.hawaii.edu, Alex_C_Stephens@yahoo.com
Alex Stephens
Affiliation:
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 USA email: boes@ifa.hawaii.edu, mnovicki@ifa.hawaii.edu, Alex_C_Stephens@yahoo.com
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Abstract

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Lithium abundances have been determined in more than 100 metal-poor halo stars both in the field and in clusters. From these data we find trends of Li with both temperature and metallicity and a real dispersion in Li abundances in the Spite Li plateau. We attribute this dispersion primarily to Li depletion (presumably due to extra mixing induced by stellar rotation) and to Galactic chemical evolution. We derive a primordial Li of 2.44$\,{\pm}\,$0.18 for A(Li)$_p$ = log N(Li/H) + 12.00. This agrees with the Li abundances predicted by the WMAP results. For stars cooler than the Li plateau we have evidence that Li depletion sets in at hotter temperatures for the higher metallicity stars than for the low-metal stars. This is the opposite sense of predictions from stellar models. The smooth transition of the Li content from the Li plateau stars to the cool stars adds weight to the inference of Li depletion in the plateau stars.

Type
Contributed Papers
Copyright
© 2005 International Astronomical Union