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Abundances in extremely metal-poor stars. Comparison of the trends of abundance ratios in giants and turnoff stars

Published online by Cambridge University Press:  23 December 2005

Monique Spite ,
Piercarlo Bonifacio ,
Roger Cayrel ,
Vanessa Hill ,
Patrick François ,
François Spite ,
Bertrand Plez ,
Eric Depagne ,
Beatriz Barbuy  and
Paolo Molaro
...Show all authors
Monique Spite
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France email: monique.spite@obspm.fr
Piercarlo Bonifacio
Affiliation:
Osservatorio Astronomico di Trieste, INAF, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
Roger Cayrel
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France email: monique.spite@obspm.fr
Vanessa Hill
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France email: monique.spite@obspm.fr
Patrick François
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France email: monique.spite@obspm.fr
François Spite
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France email: monique.spite@obspm.fr
Bertrand Plez
Affiliation:
GRAAL, Université de Montpellier II, F-34095 Montpellier Cedex 05, France
Eric Depagne
Affiliation:
European Southern Observatory, Casilla 19001, Santiago 19, Chile
Beatriz Barbuy
Affiliation:
IAG, Depto. de Astronomia, Univ. de São Paulo, CP 3386, BR 01060-970 São Paulo, Brazil
Paolo Molaro
Affiliation:
Osservatorio Astronomico di Trieste, INAF, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
Timothy Beers
Affiliation:
Department of Physics & Astronomy and Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
Johannes Andersen
Affiliation:
Niels Bohr Institute, Astronomy, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
Birgitta Nordström
Affiliation:
Niels Bohr Institute, Astronomy, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark Lund Observatory, Box 43, SE-221 00 Lund, Sweden
Francesca Primas
Affiliation:
European Southern Observatory, Karl Schwarzschild-Str. 2, D-85749 Garching b. München, Germany
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Abstract

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As part of a study of the detailed abundance patterns in extremely metal-poor stars, we have compared our samples of giants and dwarfs with two samples of dwarfs measured by different teams. For most elements the abundances are in good agreement, but for C, Na, and Al we show that the atmospheric abundances are different in dwarfs and in giants. For C the difference could be explained by “atmospheric effects” or by the influence of the first dredge-up, but for Na and Al deep mixing inside the stars must be invoked. Until now, such deep mixing has not been observed in metal-poor field stars. An excess scatter in [Mg/Fe] in giants remains unexplained.

Keywords

Stars: abundancesstars: atmospheresstars: Population IIstars: subdwarfsstars: supernovae: generalnucleosynthesis
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 1 , Symposium S228: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution , May 2005 , pp. 185 - 193
Copyright
© 2005 International Astronomical Union

Footnotes

Based on observations made with the ESO Very Large Telescope at Paranal Observatory, Chile (VLT Large Programme “First Stars”, ID 165.N-0276, P.I. R. Cayrel).