EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 486/3 Article
Free access article

Issue A&A
Volume 486, Number 3, August II 2008
Page(s) 941 - 950
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:200809405
Published online 09 June 2008



A&A 486, 941-950 (2008)
DOI: 10.1051/0004-6361:200809405

Abundance variations in the globular cluster M71 (NGC 6838)

A. Alves-Brito1, R. P. Schiavon2, B. Castilho3, and B. Barbuy1

1  Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, São Paulo 05508-900, Brazil
    e-mail: [abrito;barbuy]@astro.iag.usp.br
2  Department of Astronomy, University of Virginia, PO Box 3818, Charlottesville, VA 22903-0818, USA
    e-mail: rps7v@mail.astro.virginia.edu
3  Laboratório Nacional de Astrofísica/MCT, CP 21, Itajubá, MG, 37500-000, Brazil
    e-mail: bruno@lna.br

Received 16 January 2008 / Accepted 22 April 2008

Abstract
Context. Abundance variations in moderately metal-rich globular clusters can give clues about the formation and chemical enrichment of globular clusters.
Aims. CN, CH, Na, Mg and Al indices in spectra of 89 stars of the template metal-rich globular cluster M71 are measured and implications on internal mixing are discussed.
Methods. Stars from the turn-off up to the Red Giant Branch (0.87 < log g < 4.65) observed with the GMOS multi-object spectrograph at the Gemini-North telescope are analyzed. Radial velocities, colours, effective temperatures, gravities and spectral indices are determined for the sample.
Results. Previous findings related to the CN bimodality and CN-CH anticorrelation in stars of M71 are confirmed. We also find a CN-Na correlation, and Al-Na, as well as an Mg2-Al anticorrelation.
Conclusions. A combination of convective mixing and a primordial pollution by AGB or massive stars in the early stages of globular cluster formation is required to explain the observations.


Key words: globular clusters: individual: M71 -- stars: abundances -- stars: atmospheres -- Galaxy: abundances



© ESO 2008


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.