\begin{table}%t4
%\centering
\par
\caption{Mean metallicities and dispersions for the branches considered in the present work and for the superclusters according to (1) \citet{helmi06}.}\label{met_grups}
\small \begin{tabular}{lcc} 
\hline \hline
 & Branches (this work) & Superclusters (1)\\
 &$\overline {{\rm [Fe/H]}}\ \ $ $\sigma_{{\rm [Fe/H]}}$&$\overline {{\rm [Fe/H]}}\ \ $ $\sigma_{{\rm [Fe/H]}}$  \\
                &($\dex$)$\ \ \ $ ($\dex$)&($\dex$)$\ \ \ $ ($\dex$) \\
                 \hline
Hercules        & $-0.15\ \     $  0.27   & $-0.13\ \      $0.2\\ 
Hyades-Pleiades & $-0.11\ \     $  0.20   & $-0.08\ \      $0.2\\
Coma Berenices  & $-0.16\ \     $  0.22   &  ...     \\
Sirius          & $-0.21\ \     $  0.21   & $-0.18\ \      $0.2\\
\hline
\end{tabular}
\end{table}