\begin{table}%T6
    \caption{Formaldehyde abundances as derived from the envelope
      model in the outer parts of the envelope ($X_{\rm out}$) and the inner
      parts of the envelope ($X_{\rm in}$). The table also includes the radius
      where the dust temperature is 100~K and 50~K, and the density at
      the radius where the dust temperature is 100~K.}
    \label{table_result_infall}
    %\centerline
{
    \begin{tabular}{l l l l l l}
      \hline
      \hline
      Source & $R_{\rm 100~\rm K}$ & $R_{\rm 50~\rm  K}$ &$n_{\rm 100~
      \rm K}$ & \Xout & \Xin\\
      & (AU) & (AU) & (cm$^{-3}$) & & \\
      \hline
      \object{NGC~1333-IRAS~4A} & 53 & 127 & 2 $\times$ 10$^{9}$ & 2
      $\times$ 10$^{-10}$ & 2 $\times$ 10$^{-8}$\\
      \object{NGC~1333-IRAS~4B} & 27 & 101 & 2 $\times$ 10$^{8}$ & 5
      $\times$ 10$^{-10}$ & 3 $\times$ 10$^{-6}$\\
      \object{NGC~1333-IRAS}2 & 47 & 153 & 3 $\times$ 10$^{8}$ & 3
      $\times$ 10$^{-10}$ & 2 $\times$ 10$^{-7}$\\
      \object{L1448-MM} & 20 & 89 & 2 $\times$ 10$^{8}$ & 7 $\times$
      10$^{-10}$ & 6 $\times$ 10$^{-7}$\\
      \object{L1448-N} & 20 & 95 & 1 $\times$ 10$^{8}$ & 3 $\times$
      10$^{-10}$ & 1 $\times$ 10$^{-6}$\\
      \object{L1157-MM} & 40 & 105 & 8 $\times$ 10$^{8}$ & 8 $\times$
      10$^{-11}$ & 1 $\times$ 10$^{-8}$\\
      \object{L1527} & 20 & 140 & 3 $\times$ 10$^{6}$ & 3 $\times$
      10$^{-10}$ & 6 $\times$ 10$^{-6}$\\
      \object{VLA1623} & 13 & 48 & 2 $\times$ 10$^{8}$ & 8 $\times$
      10$^{-10}$ & -\\ 
      \hline
      \object{IRAS16293-2422}$^{{a}}$ & 133 & 266 & 1 $\times$
      10$^{8}$ & 1 $\times$ 10$^{-9}$ & 1 $\times$ 10$^{-7}$\\
      \hline
    \end{tabular}}
\par
    \medskip
      $^{{a}}$ {From \citet{Ceccarelli00b}.}
\end{table}