**Table 2:** Astrometric parameters of $\alpha$ Cen A-B.
Barycenter RA (epoch 1991.25, ICRS)^a	14:39:40.216
Barycenter Dec (epoch 1991.25, ICRS)^a	-60:50:13.58
Proper motion RA (mas)	-3642.95
Proper motion Dec (mas)	694.75
Radial velocity (km/s)	-20
Galactic long. ( $^\circ$ )	315.73
Galactic lat. ( $^\circ$ )	-0.68
Parallax (mas)^b	$747.1 \pm 1.2$
Semi-major axis a ('')^c	17.59
Period P (yr)^c	79.9
Excentricity e^c	0.519
Inclination i ( $^\circ$ )^c	79.23
Long. of ascending node $\Omega$ ( $^\circ$ )^c	204.82
Longitude of pericenter $\omega$ ( $^\circ$ )^c	231.80
Reference epoch^c	1955.59
$M_{\rm A}$ ( $M_\odot$ )^d	1.10
$M_{\rm B}$ ( $M_\odot$ )^d	0.91

^a From Hipparcos (ESA 1997).
^b Parallax from Söderhjelm (1999).
^c Orbital elements from Pourbaix (2000).
^d Masses from Thévenin et al. (2002).