\begin{table}%t1
\caption{Parameters for low-mass protostellar envelopes.}\label{table:results}  
%\centerline
 {\small 
\begin{tabular}{l l}  
\hline \hline       
\multicolumn{2}{c}{Variables} \\
 \hline\noalign{\smallskip}
$n_{\rm{H}_2}$(1000~AU) (10$^6$~cm$^{-3}$)  & 0.4, 1, 5\\
$p$ & 1.5, 2.0\\
Luminosity ($L_{\odot}$)& 2, 7, 25\\
$X_0$ (water) & $10^{-4}$, $10^{-6}$\\
$X_{\rm{d}}$ (water) & $10^{-6}$, $10^{-7}$, $10^{-8}$\\
 \hline
\multicolumn{2}{c}{Fixed parameters} \\
Distance & 150 pc \\
Stellar temperature & 5000~K \\
Gas temperature & =$T_{\rm{dust}}$\\
$R_{\rm{in}}$ (inner radius) & 250~K \\
$R_{\rm{out}}$ (outer radius) & 200 $R_{\rm{in}}$\\ 
$r_0$ & 1000 AU \\
Water freeze-out & 100~K \\
$o$:$p$ ratio H$_2$O$^{a}$ & 3:1 \\
$o$:$p$ ratio H$_2$ & 1:1\\
Dust properties & OH 5$^{b}$\\
Velocity dispersion $\Delta V$ & 1.67~km~s$^{-1}$ \\
 \hline
\end{tabular} }
\medskip
$^{a}$ For the L483 models, ortho-, and para-water were modeled independently. See Sect.~3;
$^{b}$~see Ossenkopf \& Henning (1994) Col.~5.
\end{table}