\begin{table}%T5
\caption{Model parameters.}
\label{m51model}
%\centering
\par
\begin{tabular}{lccccccc}
\hline\hline
\noalign{\smallskip} 
Model & \multicolumn{3}{c}{Component 1}    	  & \multicolumn{3}{c}{Component 2}  		  & Relative\\
     & Kinetic	    & Gas	 & CO column   	  & Kinetic 	& Gas 	      	   & CO column    & $J=2{-}1$ $\co$ \\
     & temperature  & density    & density     	  & temperature & density     	   & density      & emission \\
     & $T_{\rm k}$  & $n(\hdeux$) & $N$(CO)/d$V$	  & $T_{\rm k}$ & $n(\hdeux$)  	   & $N$(CO)/d$V$ & component\\
     & (K)     	    & ($\cc$)    & ($\cmdeux\ (\kms)^{-1}$) & (K) 	& ($\cc$) & ($\cmdeux\ (\kms)^{-1}$)  & 1:2 \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
1 (Center) & 100 &   100 & $1.0\times10^{17}$ &  60 &   1000 &  $3.0\times10^{17}$ & 0.65:0.35 \\
2 (Center) & 150 &  1000 & $0.6\times10^{17}$ &  20 &   3000 &  $3.0\times10^{17}$ & 0.55:0.45 \\
3 (Arm) & 100 &   100 & $1.0\times10^{17}$ & 150 &   1000 &  $3.0\times10^{17}$ & 0.80:0.20 \\
\hline
\end{tabular}
\end{table}