\begin{table}%t2
\caption{\label{alfcen_astrom_params}Astrometric parameters of $\alpha$~Cen~A-B.}
\small%\centerline
{
\begin{tabular}{lc}
\hline
\hline
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 \\
\hline
\end{tabular}}
\smallskip
 $^{{a}}$ From Hipparcos (ESA~\cite{esa97}).
 $^{{b}}$ Parallax from S\"oderhjelm~(\cite{soderhjelm99}).
 $^{{c}}$ Orbital elements from Pourbaix~(\cite{pourbaix00}).
 $^{{d}}$ Masses from Th\'evenin et~al.~(\cite{thevenin02}).
\end{table}