Calibrations of Centauri A & B
P. Morel 1,
J. Provost 1,
Y. Lebreton 2,
F. Thévenin 1 and
G. Berthomieu 1
Received 6 July 2000 / Accepted 28 September 2000
Detailed evolutionary models of the visual binary Centauri, including pre main-sequence evolution, have been performed using the masses recently determined by Pourbaix et al. (1999). Models have been constructed using the CEFF equation of state, OPAL opacities, NACRE thermonuclear reaction rates and microscopic diffusion. A -minimization is performed to derive the most reliable set of modeling parameters , where is the age of the system, the initial helium content, the initial metallicity and, and the convection parameters of the two components. Using the basic Böhm-Vitense (1958) mixing-length theory of convection, we derive . We obtain a noticeably smaller age than estimated previously, in agreement with Pourbaix et al. (1999), mainly because of the larger masses. If convective core overshoot is considered we get . The use of Canuto & Mazitelli (1991 , 1992) convection theory leads to the set . Using the observational constraints adopted by Guenther & Demarque (2000), and the basic mixing-length theory, we obtain and surface lithium depletions close to their observed values.
A seismological analysis of our calibrated models has been performed. The determination of large and small spacings between the frequencies of acoustic oscillations from seismic observations would help to discriminate between the models of Cen computed with different masses and to confirm or rule out the new determination of masses.
Key words: convection diffusion stars: binaries: visual stars: evolution stars: fundamental parameters stars: individual: ff Cen
Send offprint requests to: P. Morel
Correspondence to: Pierre.Morel@obs-nice.fr
© European Southern Observatory (ESO) 2000
Online publication: December 11, 2000