EDP Sciences
Free access
Issue A&A
Volume 449, Number 2, April II 2006
Page(s) 655 - 671
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20054377

A&A 449, 655-671 (2006)
DOI: 10.1051/0004-6361:20054377

CNO in evolved intermediate mass stars

R. Smiljanic1, B. Barbuy1, J. R. De Medeiros2 and A. Maeder3

1  Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, 05508-900 São Paulo, SP, Brazil
    e-mail: [rodolfo;barbuy]@astro.iag.usp.br
2  Universidade Federal do Rio Grande do Norte, Departamento de Física, Campus Universitário, 59072-970 Natal, RN, Brazil
    e-mail: renan@dfte.ufrn.br
3  Geneva Observatory, 1290 Sauverny, Switzerland
    e-mail: Andre.Maeder@obs.unige.ch

(Received 19 October 2005 / Accepted 4 November 2005)

Abstract
In order to investigate the possible influence of rotation on the efficiency of the first dredge-up we determined atmospheric parameters, masses, and abundances of carbon, nitrogen, and oxygen in a sample of evolved intermediate mass stars. We used high resolution spectra and conducted a model atmosphere analysis. The abundances were calculated through spectral synthesis and compared to the predictions of rotating and non-rotating evolutionary models. Almost all those objects in our sample where carbon and nitrogen abundances could be determined show signs of internal mixing. The stars, however, seem to be mixed to different extents. Among the mixed stars we identify five in our sample with abundances in agreement with the non-rotating models, four stars that seem to be mixed beyond that, and one star that seems to be slightly less mixed than predicted for the first dredge-up. There are also five stars that seem to be slightly more mixed than expected, but their abundances are in marginal agreement with both rotating and non-rotating models. Such differences in the extent of the mixing are not predicted by the standard models and imply the action of other mixing mechanisms than solely the convective dredge-up. We also identified for the first time an important correlation between the [N/C] ratio and the stellar mass.


Key words: stars: fundamental parameters -- stars: abundances -- stars: supergiants -- stars: rotation

SIMBAD Objects




© ESO 2006

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.

Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

Mirror sites: CDS | EDP Sciences
  RSS feeds
© The European Southern Observatory (ESO)