EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 404/3 Article
Free access article

Issue A&A
Volume 404, Number 3, June IV 2003
Page(s) 1087 - 1097
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030570



A&A 404, 1087-1097 (2003)
DOI: 10.1051/0004-6361:20030570

The diameters of $\alpha$ Centauri A and B

A comparison of the asteroseismic and VINCI/VLTI views
P. Kervella1, F. Thévenin2, D. Ségransan3, G. Berthomieu2, B. Lopez4, P. Morel2 and J. Provost2

1  European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile
2  Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
3  Observatoire de Genève, 1290 Sauverny, Switzerland
4  Département Fresnel, UMR CNRS 6528, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France

(Received 20 January 2003 / Accepted 9 April 2003 )

Abstract
We compare the first direct angular diameter measurements obtained on our closest stellar neighbour, $\alpha$ Centauri, to recent model diameters constrained by asteroseismic observations. Using the VINCI instrument installed at ESO's VLT Interferometer (VLTI), the angular diameters of the two main components of the system, $\alpha$ Cen A and B, were measured with a relative precision of 0.2% and 0.6% respectively. Particular care has been taken in the calibration of these measurements, considering that VINCI is estimating the fringe visibility using a broadband K filter. We obtain uniform disk angular diameters for $\alpha$ Cen A and B of $\rm\theta_{\rm UD}[A] = 8.314 \pm 0.016$ mas and $\rm\theta_{\rm UD}[B] = 5.856 \pm 0.027$ mas, and limb darkened angular diameters of $\rm\theta_{\rm LD}[A] = 8.511 \pm 0.020$ mas and $\rm\theta_{\rm LD}[B] = 6.001 \pm 0.034$ mas. Combining these values with the parallax from Söderhjelm (1999), we derive linear diameters of $D[{\rm A}] = 1.224 \pm 0.003\ D_{\odot}$ and $D[{\rm B}] = 0.863 \pm 0.005\ D_{\odot}$. These values are compatible with the masses published by Thévenin et al. (2002) for both stars.


Key words: techniques: interferometric -- stars: binaries: visual -- stars: evolution -- stars: oscillations -- stars: fundamental parameters -- stars: individual: $\alpha$ Cen

Offprint request: P. Kervella, pierre.kervella@eso.org

SIMBAD Objects



© ESO 2003


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.