\begin{table}%t8
%\centering
\par
\caption{Inferred inner abundances $x_{\rm XDR}$ from jump models assuming 
the emission to come from the X-ray dominated inner $1000$~AU envelope. The 
average temperature $T_{\rm av}$ and hydrogen density $n_{\rm H,~ av}$ of the 
inner $1000$~AU region are also given.}
\label{tabjx}
\small
\begin{tabular}{lllrrrr} \hline\hline 
Source & $T_{\rm av}$ (K) & $n_{\rm H,~ av}$ (cm$^{-3}$) & CN & NO & CO$^+$ & SO$^+$ \\ \hline 
AFGL 2591 & 180 & $4\times 10^6$ & $8\times 10^{-07}$ & $4\times 10^{-06}$ & $2\times 10^{-09}$ & $3\times 10^{-09}$ \\
W3 IRS 5 & 490 & $6\times 10^7$ & $5\times10^{-07}$ & $5\times 10^{-06}$ & $5\times 10^{-10}$ & $3\times 10^{-08}$ \\
IRAS 16293 & 50 & $2\times 10^8$ & $8\times 10^{-11}$ & ... & $2\times 10^{-12}$ & $\lesssim$$5\times 10^{-12}$ \\ \hline
\end{tabular}
\end{table}