\begin{table}%t7
%\centering
\par
\caption{\label{tab7}Parameters representing the final model.}
\begin{tabular}{ll} 
\hline\hline 
Parameter & Value\\  
\hline
{\it Ionizing source} &\\
{\it Model atmosphere} & Rauch H-Ni \\
$T_{\rm eff}  $ &160~000 K \\
Log $g$    & 6.00 \\
Luminosity & 600 $L_{\smallsun}$\\
\\
{\it Nebula}    & \\
\\Density profile & See Fig.~\ref{sketch}  \\
Abundance & H     \hskip 1.0cm He    \hskip 0.9cm C    \hskip 1.0cm N \\
          & 12.000\hskip 0.3cm 11.000\hskip 0.6cm 7.900\hskip 0.4cm 7.641 \\
          & O     \hskip 1.0cm Ne    \hskip 0.9cm Mg   \hskip 0.9cm Si \\
          & 8.321 \hskip 0.4cm 7.799\hskip 0.4cm 7.031 \hskip 0.5cm 6.455\\
          & S     \hskip 1.0cm Cl    \hskip 0.9cm Ar  \hskip 0.8cm  \\
          & 6.648 \hskip 0.4cm 5.049\hskip 0.6cm 6.213 \hskip 0.4cm\\
Size      &$10\arcsec$ (radius)\\
Distance  & 1.50~kpc\\
Dust grains &  Silicates of single size $1.0~\mu$m; \\
inner radius & 2.244e16~cm  \\
outer radius & 2.244e17~cm \\
Filling factor & 1.0\\
\hline
\end{tabular}
\end{table}