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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:  01 August 2006

Monique Spite ,
Piercarlo Bonifacio ,
Roger Cayrel ,
François Spite ,
Vanessa Hill ,
Johannes Andersen ,
Beatriz Barbuy ,
Timothy Beers ,
Eric Depagne  and
Patrick François
...Show all authors
Monique Spite
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France
Piercarlo Bonifacio
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France
Roger Cayrel
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France
François Spite
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France
Vanessa Hill
Affiliation:
GEPI, Observatoire de Paris-Meudon, F-92125 Meudon Cedex, France
Johannes Andersen
Affiliation:
Astron. Obs., NBIfAFG, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
Beatriz Barbuy
Affiliation:
IAG, Universidade de Sao Paulo, Depto. de Astronomia, rua do Matao 1226, Sao Paulo 05508-900, Brazil
Timothy Beers
Affiliation:
Department of Physics & Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824, USA
Eric Depagne
Affiliation:
ESO, 3107 Alonso de Cordova, Vitacura, Casilla 19001, Santiago 19, Chile
Patrick François
Affiliation:
ESO, 3107 Alonso de Cordova, Vitacura, Casilla 19001, Santiago 19, Chile
Paolo Molaro
Affiliation:
Osservatorio Astronomico di Trieste, INAF, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
Birgitta Nordström
Affiliation:
Astron. Obs., NBIfAFG, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark Lund Observatory, Box 43, SE-221 00 Lund, Sweden
Bertrand Plez
Affiliation:
GRAAL, Université de Montpellier II, F-34095 Montpellier Cedex 05, France
Francesca Primas
Affiliation:
ESO, Karl Schwarzschild-Str. 2, D-85749 Garching b. München, Germany
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Abstract

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We show that in a sample of Extremely Metal-Poor (EMP) giants (<[Fe/H]>=−3.1) all the stars with a luminosity higher than logL/L⊙ ≈ 2.6 present the characteristics of a mixing of the surface with the H-burning layer: low abundance of carbon and high abundance of nitrogen. In these “mixed stars” the lithium abundance and the ratio 12C/13C are very low. Some of these stars are also Na or/and Al rich.

Keywords

Stars: abundancesstars: atmospheresstars: Population IIsubdwarfssupernovaenucleosynthesis
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S239: Convection in Astrophysics , August 2006 , pp. 280 - 285
Copyright
Copyright © International Astronomical Union 2007

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