\begin{table}%t2
%\centering
\par
      \caption{\label{tab:model}Parameters of the reference model (\refmod).}
          \begin{tabular}{lccc}   
          \hline  \hline \noalign{\smallskip}
     Component$\rightarrow$  & Hot\tablefootmark{a} (H$_{\rm C}$) & Warm ($W_{\rm C}$) &
     Extended ($E_{\rm C}$)\\  
\hline
Radius (pc) &   $23$       &  $120$   &    $610$ \\
$T_{{\rm dust}}$ (K)  &  $400{-}150$  & $95$   &   $41$ \\
$\tau_{{\rm 100~\mu m}}$ &  $0.4$     & $1.0$   &   $0.5$ \\
$L$ (\Lsun) & $7.5\times10^{11}$ & $1.9\times10^{12}$ & $9.6\times10^{11}$ \\
Gas Mass\tablefootmark{b} (\Msun) & $1.9\times10^{6}$ & $5.9\times10^{8}$ &
$7.7 \times 10^{9}$ \\ 
$N({\rm H_2O})$ (cm$^{-2}$)&$-$ & $5.2\times10^{17}$ & $2.0\times10^{16}$ \\
$V_{{\rm turb}}$ (km~s$^{-1}$) & $-$ & 60\tablefootmark{d} & 40 \\
$n({\rm H_2})^{{\rm c}}$ (cm$^{-3}$) & $-$ & $1.5\times10^6$ &
 $5 \times 10^5$ \\ 
$T_{\rm gas}$\tablefootmark{c} (K) & $-$ & 150 & 100\\ 
\hline
\end{tabular} 
\tablefoot{\tablefoottext{a}{The hot component does not contribute to the H$_2$O  emission;}
\tablefoottext{b}{a gas-to-dust mass ratio of 100 is assumed.}
\tablefoottext{c}{These parameters are not well determined for $W_{\rm C}$,  as the excitation is dominated by radiative pumping.}
\tablefoottext{d}{From \cite{dow98}.}}
   \end{table}