EDP Sciences
Free access
Issue A&A
Volume 417, Number 1, April I 2004
Page(s) 235 - 246
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20034203



A&A 417, 235-246 (2004)
DOI: 10.1051/0004-6361:20034203

Analysis of $\alpha$ Centauri AB including seismic constraints

P. Eggenberger1, C. Charbonnel1, 2, S. Talon3, G. Meynet1, A. Maeder1, F. Carrier1 and G. Bourban1

1  Observatoire de Genève, 51 chemin des Maillettes, 1290 Sauverny, Suisse
2  Laboratoire d'Astrophysique de Toulouse, CNRS UMR 5572, OMP, 14 Av. E. Belin, 31400 Toulouse, France
3  Département de Physique, Université de Montréal, CP 6128, Station centre-ville, 2900 Bld. Édouard-Montpetit, Montréal PQ H3C 3J7, Canada

(Received 15 August 2003 / Accepted 6 December 2003 )

Abstract
Detailed models of $\alpha$ Cen A and B based on new seismological data for $\alpha$ Cen B by Carrier & Bourban ([CITE]) have been computed using the Geneva evolution code including atomic diffusion. Taking into account the numerous observational constraints now available for the $\alpha$ Cen system, we find a stellar model which is in good agreement with the astrometric, photometric, spectroscopic and asteroseismic data. The global parameters of the $\alpha$ Cen system are now firmly constrained to an age of $t=6.52 \pm
0.30$ Gyr, an initial helium mass fraction $Y_{\mathrm{i}}=0.275 \pm 0.010$ and an initial metallicity $(Z/X)_{\mathrm{i}}=0.0434 \pm 0.0020$. Thanks to these numerous observational constraints, we confirm that the mixing-length parameter $\alpha$ of the B component is larger than the one of the A component, as already suggested by many authors (Noels et al. [CITE]; Fernandes & Neuforge [CITE]; Guenther & Demarque [CITE]): $\alpha_{\mathrm{B}}$ is about 8% larger than $\alpha_{\mathrm{A}}$ ( $\alpha_{\mathrm{A}}=1.83 \pm 0.10$ and $\alpha_{\mathrm{B}}=1.97 \pm 0.10$). Moreover, we show that asteroseismic measurements enable to determine the radii of both stars with a very high precision (errors smaller than 0.3%). The radii deduced from seismological data are compatible with the new interferometric results of Kervella et al. ([CITE]) even if they are slightly larger than the interferometric radii (differences smaller than 1%).


Key words: stars: binaries: visual -- stars: individual: $\alpha$ Cen -- stars: evolution -- stars: oscillations

Offprint request: P. Eggenberger, Patrick.Eggenberger@obs.unige.ch

SIMBAD Objects



© ESO 2004

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)