\begin{table}%t2
\caption{\label{tab:col}CH$^+$ Column densities.}\vspace*{-2mm}
%\centering
\par
\begin{tabular}{lcc}
\hline\hline \noalign{\smallskip}
Component & $T_{\rm ex}$ & $N(\CHp)$ \\
          & K     & cm$^{-2}$\\
\hline \noalign{\smallskip}
Broad line emission   &   $40~ {\rm K}< T_{\rm ex} < 100~{\rm K} $ & $2.2 \times 10^{13}$ \\  
Foreground absorption& 3.0 &  ${>}1.7 \times 10^{14}$ \\
\hline 
\end{tabular}\vspace*{-3mm}
\end{table}