\begin{table}%t2
\caption{Physical parameters used to model the PDR of the molecular cloud \object{S140}.}
\label{parametres_physiques}
\small%\centerline
 {
\begin{tabular}{l l}
\hline \hline
Cloud size ($A_{\rm V}$) & $20$ \\
Proton density ($n_{{\rm H}}$) & $2 \times 10^{4}~{\rm cm}^{-3}$ \\
Isotropic radiation field (both sides) & $1$ (Draine) \\
Additional radiation field source & B 0 V Star \\
Star distance & $1.85~{\rm pc}$ \\
Corresponding Habbing factor	& $\sim$$120$\\
Cosmic rays ionization rate per \element{H} atom & $5\times10^{-17}~{\rm s}^{-1}$ \\
Turbulent velocity dispersion & $2 \times 10^{5}~{\rm cm~s}^{-1}$ \\
$R_{\rm V}=A_{\rm V}/E(B-V)$ & $3.1$ \\
$C_{\rm D} = N_{\element{H}}/E(B-V)$ & $5.80 \times 10^{21}~{\rm cm}^{-2}$ \\
Dust albedo & $0.42$ \\
Diffusion anisotropy factor ($g= \langle \cos (\theta ) \rangle$) & $0.60$ \\
Dust to gas mass ratio & $0.01$ \\
Grain mass density &  $2.59~{\rm g}~{\rm cm}^{-3}$ \\
Grains distribution index (MRN) & $-3.5$ \\
Grains minimum radius & $3.0 \times 10^{-7}~{\rm cm} $ \\
Grains maximum radius & $3.0 \times 10^{-5}~{\rm cm} $ \\
\hline
\end{tabular}}
\medskip
References --  MRN: Mathis et~al. (1977).
\end{table}