\begin{table}%t3
\par
\caption {\label{Tabla3}Values of the density $\rho$, the surface gravity $g$, and the encounter velocity $v_{\rm i}$ used for Pluto and Charon.
}
%\centering
\par
\begin{tabular}{lcc}
\hline \hline \noalign{\smallskip}
 & Pluto   &  Charon  \\
\hline 
$\rho$ (g cm$^{-3}$) &  2.03   &  1.65     \\
$g$ (cm s$^{-2}$) & 66.4  &  27.9   \\
$v_{{\rm i}}$ (km s$^{-1}$) & 1.9  &   1.6    \\
\hline
\end{tabular}
\end{table}