\begin{table}%t2
%\centering
\par
\caption{Observational constraints for $\alpha$~Cen~A and B. References: (1) S\"oderhjelm (\cite{so99}), (2) Pourbaix et~al. (\cite{po02}),
(3) this paper, (4) derived from the other observational measurements (see text), (5) Kervella et~al. (\cite{ke03}),
(6) Bouchy \& Carrier (\cite{bo02}) and (7) Carrier \& Bourban (\cite{ca03}).}\label{tab:constraints}
\begin{tabular}{cccc}
\hline
\hline
 & \multicolumn{1}{c}{$\alpha$~Cen~A} & \multicolumn{1}{c}{$\alpha$~Cen B} & \multicolumn{1}{c}{References} \\ \hline
\par
$\pi$ [mas]& \multicolumn{2}{c}{$747.1 \pm 1.2$} & (1) \\
$M/M_{\odot}$  & $1.105 \pm 0.0070$ & $0.934 \pm 0.0061$ & (2) \\
$V$ [mag] & $-0.003 \pm 0.006$  & $1.333 \pm 0.014$ & (3) \\
$L/L_{\odot}$ & $1.522 \pm 0.030$ & $0.503 \pm 0.020$ & (4) \\
$T_{{\rm eff}}$ [K]& $5810 \pm 50$ & $5260 \pm 50$ & (3) \\
$[$Fe/H$]_{{\rm s}}$ &  $0.22 \pm 0.05$ & $0.24 \pm 0.05$ & (3) \\
$\theta$ [mas] &  $8.511 \pm 0.020$ & $6.001 \pm 0.034$ & (5)\\
$R/R_{\odot}$ & $1.224 \pm 0.003$ & $0.863 \pm 0.005$ & (5) \\
$\Delta \nu_{0}$ [$\mu$Hz] & $105.5 \pm 0.1$  & $161.1 \pm 0.1$ & (6), (7) \\
$\delta \nu_{02}$ [$\mu$Hz] & $5.6 \pm 0.7$ & $8.7 \pm 0.8$ &  (6), (7) \\
\hline
\end{tabular}
\end{table}