\begin{table}%t1
\caption{Parameters of the Sa, Sb, Sc galaxy models. The unit system is $G=1$: the mass unity is $U_{\rm m}=2.26$~$\times$ $10^9~M_\odot$, the length unity is $U_{\rm r}=1.02$~kpc.}
\label{tab:param}
%\centering
\small
\begin{tabular}{c c c c c c c c}
\hline\hline 
 Run & $M_{\rm d}$ & $M_{\rm b}$ & Gas   &$a_{\rm d}$ & $a_{\rm g}$ & $M_{\rm h}$& $b_{\rm h}$ \\
\hline
Sa   & 40    & 12.7  & $2\%$ & 4    & 6   & 146.3  & 29.4   \\
Sb   & 30    & 5     & $5\%$ & 5    & 7.5 & 118.9  & 24.8   \\
Sc   & 20    & 2     & $7\%$ & 6    & 9   & 92.8   & 20.9   \\
\hline
\end{tabular} 
\end{table}