\begin{table}%T9
\caption{ Supposing a homogeneous distribution of the PAH molecules in
a halo around the central star, with a radius of the size of the
ISO-SWS beam (11\arcsec) at the appropriate distance, the PAH particle density $\rho$ is
computed based on the $L_{{\rm PAH}}/L_{\uv}$ ratio. All objects in which PAH
emission is detected are adopted in this table and are listed
according to decreasing PAH-over-UV luminosity.
 \label{NISO}}	  
%\centering
\par
\begin{tabular}{cccc}
 \hline\hline
 \multicolumn{4}{c}{\bf Does PAH emission emanate from a halo?}\\ \hline 
 \multicolumn{1}{c}{Object} &
 \multicolumn{1}{c}{Group} &
 \multicolumn{1}{c}{$L_{{\rm PAH}}/L_{\uv}$} &
 \multicolumn{1}{c}{$\rho$} \\ 
                         &     &               & [$\cm^{-3}$]     \\
\hline
\noalign{\smallskip} 
 \object{Elias 3-1}               & I   &    0.36       & $5.51 10^{-4}$   \\
 \object{RR Tau}                  & II  & $2.5\times 10^{-2}$ & $3.82\times 10^{-5}$   \\
 \object{HD~34700}                & I   & $1.1\times 10^{-2}$ & $8.13\times 10^{-5}$   \\
 \object{HD~97048}                & I   & $1.1\times 10^{-2}$ & $1.51\times 10^{-5}$   \\
 \object{HD~34282}                & I   & $1.0\times 10^{-2}$ & $6.21\times 10^{-6}$   \\
 \object{VX Cas}                  & II  & $7.7\times 10^{-3}$ & $3.00\times 10^{-6}$   \\
 \object{HD~169142}               & I   & $6.8\times 10^{-3}$ & $1.14\times 10^{-5}$   \\
 \object{HD~100546}               & I   & $6.4\times 10^{-3}$ & $1.51\times 10^{-5}$   \\
 \object{HD~179218}               & I   & $5.5\times 10^{-3}$ & $5.60\times 10^{-6}$   \\
 \object{HD~100453}               & I   & $5.2\times 10^{-3}$ & $1.14\times 10^{-5}$   \\
 \object{HD~95881}                & II  & $4.2\times 10^{-3}$ & $8.70\times 10^{-6}$   \\
 \object{Wra 15-1484}             & II  & $3.5\times 10^{-3}$ & $1.14\times 10^{-6}$   \\
 \object{HD~139614}               & I   & $3.3\times 10^{-3}$ & $5.78\times 10^{-6}$   \\
 \object{VV Ser}                  & II  & $2.6\times 10^{-3}$ & $1.93\times 10^{-6}$   \\
 \object{AB Aur}                  & I   & $2.2\times 10^{-3}$ & $3.87\times 10^{-6}$   \\
 \object{HD~142666}               & II  & $2.0\times 10^{-3}$ & $3.42\times 10^{-6}$   \\
 \object{HD~135344}               & I   & $1.6\times 10^{-3}$ & $2.86\times 10^{-6}$   \\
 \object{CD$-$42$^\circ$11721}    & I   & $1.3\times 10^{-3}$ & $8.16\times 10^{-7}$   \\
 \object{HD~144432}               & II  & $9.8\times 10^{-4}$ & $1.65\times 10^{-6}$   \\
 \object{BD+40$^\circ$4124}       & I?  & $9.3\times 10^{-4}$ & $2.31\times 10^{-7}$   \\
 \object{HD~31648}                & II  & $8.5\times 10^{-4}$ & $1.58\times 10^{-6}$   \\
 \object{HD~163296}               & II  & $7.1\times 10^{-4}$ & $1.42\times 10^{-6}$   \\
 \object{HD~142527}               & I   & $6.9\times 10^{-4}$ & $1.15\times 10^{-6}$   \\
 \object{HD~141569}               & II  & $5.3\times 10^{-4}$ & $1.31\times 10^{-6}$   \\
 \object{MWC 1080}                & I   & $1.4\times 10^{-4}$ & $1.54\times 10^{-8}$   \\
 \object{MWC 297}                 & III & $6.8\times 10^{-5}$ & $6.64\times 10^{-8}$   \\
 \object{HD~200775}               & I   & $3.1\times 10^{-5}$ & $1.72\times 10^{-8}$   \\
 \hline			  
\end{tabular}		  
\end{table}