\begin{table}%t5
\caption{\label{4:tab:column}Overview of the envelope properties$^a$.}
%\centerline
 {\small \begin{tabular}{l l l l l l l l}
\hline \hline\noalign{\smallskip}
Source & $R_{\rm{core}}$ & $M_{\rm{envelope}}$ & $N$(H$_2$)$^a$ & $N$(C$^{18}$O)& $N$(H$^{13}$CO$^+$) & $\tau_{\rm{CO 3-2}}$ & $\tau_{\rm{HCO^+ 4-3}}$  \\  
 & ($''$) & ($M_\odot$) & (10$^{22}$~cm$^{-2}$) & (10$^{15}$~cm$^{-2}$) & (10$^{15}$ cm$^{-2}$) & & \\
\hline
\multicolumn{7}{c}{Chamaeleon} \\
%\hline
Ced 110 IRS 4 & 20 & 0.07 &5.0/--  & 8.3 & 1.4& 181 & 6.7  \\ % & 4.3
%B35 & 3.6 & 6.0 & - & 4.5 & $<$1.8  & 4.5\\
Ced 110 IRS 6 & 20 & 0.04 &3.3/-- & 5.5 & -- & 90 & $<$13 \\ %& 4.8 
Cha IRS 6a    & -- & --    &0.26/-- & 0.43 &-- & -- & -- \\ 
Cha IRN       & 20 & 0.17 &4.3/-- & 7.2 &-- & 400 & $<$5.2\\ 
Cha INa 2     & -- & --    &3.8/-- & 6.3 &-- & 150 & -- \\
\noalign{\smallskip}\hline \noalign{\smallskip}
\multicolumn{7}{c}{Corona australis$^b$} \\
%\hline
CrA IRAS 32 &44  & 0.8 &10.5/21.2* & 17.5 & 3.0& 257 & 16 \\ 
HH100-off   & 45 & 1.6 &12.4/35.2* & 20.7 & -- & 130 & $<$0.9\\  
RCrA IRS 5  & 43 &  1.7 &20.7/24.5* & 35.1 & 4.8 & 189 & 10 \\ 
RCrA IRS 7A & 48 &  6.3$^c$&21.2/30.5* & 35.3 & 8.9 & 117 & 7.7 \\ 
RCrA IRS 7B & 48 &  6.3$^c$&23.8/30.5* & 39.7 & 12.3 & 156 & 10\\  
RCrA TS 3.5 & -- & -- &--/-- & -- &  --&  --  & -- \\
\hline  
\multicolumn{7}{c}{Isolated} \\
%\hline
HH 46$^d$ & 60 & 5.1 & 8.1/18.2* & 13.5 & 6.1 & 103 & 16\\  
IRAS 07178-4429 & -- & -- &5.5/-- & 9.2 &-- & 123.9 & $<$8\\  
IRAS 12496-7650 & 25 & 0.4 &3.0/-- & 5.0 & -- & 25 & $<$3.1  \\  
IRAS 13546-3941 & -- & -- &5.5/-- & 9.2 &-- & 123 & -- \\  
IRAS 15398-3359 & 25 & 0.5 &1.9/-- & 3.2 & -- & 79 & --\\
\hline  
\end{tabular}}
\medskip
The column density of H$_2$ is derived from that of C$^{18}$O assuming
H$_2$/C$^{18}$O~=~$5.5 \times 10^6$. 
If 850~$\mu$m data are available in \citet{diFrancesco08}, column densities 
based on the dust emission are also computed. 
These numbers are indicated as the second
entry with an asterisk. Both column densities are within the same 18 $''$ beam; $^b$~mass estimates in the RCrA region may be severely overestimated due to presence of extended cloud material; $^c$ RCrA IRS 7A and 7B cannot be distinguished in the sub-millimeter continuum maps; the value refers to the core containing both sources; $^d$~for a thorough discussion on the mass of HH 46, see \citet{vanKempen09a}.
\end{table}