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12C/13C ratios in giants of open clusters

Smiljanic, Rodolfo ; Gauderon, R. ; North, P. ; Barbuy, B. ; Charbonnel, C. ; Mowlavi, N.

In: Proceedings of the International Astronomical Union, 2006, vol. 2, no. S239, p. 298-300

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    Titre
    • 12C/13C ratios in giants of open clusters
    Auteur
    • Smiljanic, Rodolfo. Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, 05508-090, São Paulo SP, Brazil email:rodolfo@astro.iag.usp.br barbuy@astro.iag.usp.br
    • Gauderon, R.. Laboratoire d'astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL) - CH 1290 Sauverny, Switzerland
    • North, P.. Laboratoire d'astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL) - CH 1290 Sauverny, Switzerland
    • Barbuy, B.. Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, 05508-090, São Paulo SP, Brazil email:rodolfo@astro.iag.usp.br barbuy@astro.iag.usp.br
    • Charbonnel, C.. Observatoire de Genève 51, Chemin des Maillettes - CH 1290 Sauverny, Switzerland
    • Mowlavi, N.. Observatoire de Genève - Integral Science Data Center, Chemin d'Ecogia 16 - CH 1290 Versoix, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Proceedings of the International Astronomical Union, 2006, vol. 2, no. S239, p. 298-300. Cambridge University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:296454
    Summary
    The carbon isotopic ratio, 12C/13C, is a tracer of the mixing events during the evolution along the giant branch, due to the conversion of 12C into 13C (and 14N) via the CN cycle. A decrease of this ratio from 90, the solar value, to 20-25, is expected due to the first dredge-up. However, ratios down to 3-4, the CN cycle equilibrium value, have been observed in giants of the field, of globular and of open clusters. Observations seem to indicate a non-standard mixing in the RGB, probably beginning in the luminosity bump, when the outward moving hydrogen burning shell crosses the molecular weight barrier left by the convective layer in its maximum extent. We are currently analyzing a sample of 24 giants in 8 open clusters for which we determined 12C/13C from high resolution, high signal to noise spectra using spectrum synthesis. In this work we discuss the general characteristics of our results in comparison to previous analyses of giants in open clusters available in the literature