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Observational signatures for depletion in the Spite plateau: solving the cosmological Li discrepancy?

Published online by Cambridge University Press:  23 April 2010

Jorge Meléndez ,
Luca Casagrande ,
Iván Ramírez ,
Martin Asplund  and
William J. Schuster
Jorge Meléndez
Affiliation:
Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal email: [email protected]
Luca Casagrande
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1317, D-85741 Garching, Germany
Iván Ramírez
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1317, D-85741 Garching, Germany
Martin Asplund
Affiliation:
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1317, D-85741 Garching, Germany
William J. Schuster
Affiliation:
Observatorio Astronómico Nacional, UNAM, Apartado Postal 877, Ensenada, BC, CP 22800, Mexico
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Abstract

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We present Li abundances for 73 stars in the metallicity range −3.5 < [Fe/H] < −1.0 using improved IRFM temperatures (Casagrande et al. 2010) with precise E(B-V) values obtained mostly from interstellar NaI D lines, and high-quality equivalent widths (σEW ~ 3%). At all metallicities we uncover a fine-structure in the Li abundances of Spite plateau stars, which we trace to Li depletion that depends on both metallicity and mass. Models including atomic diffusion and turbulent mixing seem to reproduce the observed Li depletion assuming a primordial Li abundance ALi = 2.64 dex (MARCS models) or 2.72 (Kurucz overshooting models), in good agreement with current predictions (ALi = 2.72) from standard BBN. We are currently expanding our sample to have a better coverage of different evolutionary stages at the high and low metallicity ends, in order to verify our findings.

Keywords

nucleosynthesis – cosmology: observations – stars: abundancesPopulation II
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S268: Light Elements in the Universe , November 2009 , pp. 211 - 214
Copyright
Copyright © International Astronomical Union 2010

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