\begin{table}%t1
%\centering
\par
\caption{\label{table1}The maximum mass $M_{\max}$, radii~$R$ and central densities $u_{\rm cent}=n_{\rm cent}/n_0$ of neutron stars.}
\small \begin{tabular}{cccccc}
\hline\hline\noalign{\smallskip}
\multicolumn{1}{c}{} & \multicolumn{1}{c}{$M_{\max}/M_{\odot}$} &
\multicolumn{1}{c}{$u_{\rm cent}$} & \multicolumn{1}{c}{$R$(km)} &
\multicolumn{1}{c}{$u_{\rm cr}\left(K^-\right)$} &
\multicolumn{1}{c}{$u_{\rm cr}\left(\overline{K}^{~0}\right)$} \\
\hline
$np$& 2.3592 & 5.648 & 11.897 & -- & -- \\
$np K^- \overline{K}^{~0}$   & 2.0632 & 5.217 & 12.691  & 3.028 & 4.869 \\
\hline 
\end{tabular}
\end{table}