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Issue A&A
Volume 392, Number 1, September II 2002
Page(s) L9 - L12
Section Letters
DOI 10.1051/0004-6361:20021074



A&A 392, L9-L12 (2002)
DOI: 10.1051/0004-6361:20021074

Letter

Asteroseismology and calibration of $\alpha$ Cen binary system

F. Thévenin1, J. Provost1, P. Morel1, G. Berthomieu1, F. Bouchy2 and F. Carrier2

1  Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
2  Observatoire de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland

(Received 24 May (2002) / Accepted 22 July (2002) )

Abstract
Using the oscillation frequencies of $\alpha$ Cen A recently discovered by Bouchy & Carrier (2001, (2002)), the available astrometric, photometric and spectroscopic data, we tried to improve the calibration of the visual binary system $\alpha$ Cen. With the revisited masses of Pourbaix et al. 2002 we did not succeed in obtaining a solution satisfying all the seismic observational constraints. Relaxing the constraints on the masses, we have found an age $t_{\rm\alpha\,Cen}=4850\pm500$ Myr, an initial helium mass fraction $Y_{\rm i} = 0.300\pm0.008$, and an initial metallicity $(Z/X)_{\rm i}=0.0459\pm0.0019$, with $M_{\rm A}=1.100\pm0.006\,M_\odot$ and $M_{\rm B}=0.907\pm0.006\,M_\odot$ for $\alpha$ Cen A & B.


Key words: stars: binaries: visual -- stars: evolution -- stars: oscillation -- stars: fundamental parameters -- stars: individual: $\alpha$ Cen

Offprint request: F. Thévenin, Frederic.Thevenin@obs-nice.fr

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