\begin{table}%t7
\caption{\label{disipation}Dissipation timescale.}  
%\centerline
 {\small \begin{tabular}{llll}
\hline\hline\noalign{\smallskip}
Source & $R_{\rm g}^1$ & Mass loss rate & Life time$^2$ \\
 & (AU) & ($M_\odot$~yr$^{-1}$) & (yr) \\
\hline \noalign{\smallskip}
MWC~137 & 124.6 & $8.9\times 10^{-6}$ & $1.1\times 10^5$   \\
LKH$\alpha$~215 & 53.4 & $3.4\times 10^{-6}$ & $2.9\times 10^5$\\
R~Mon & 71.2 & $4.1\times 10^{-6}$ & $2.4\times 10^5$ \\
Z~CMa & 106.8 & $6.1\times 10^{-6}$ &  $1.6\times 10^5$ \\
MWC~297 & 80 & $6.0\times 10^{-6}$ & $1.7\times 10^5$ \\
MWC~1080 & 89 & $4.6\times 10^{-6}$ &  $2.2\times 10^5$ \\
\hline
\end{tabular}}
\medskip
$^1$ Gravitational radius calculated following expression~(1) by \cite{ale07} ; $^2$~time required to disperse a 1~$M_\odot$ disk. 
%\vspace*{4mm} 
\end{table}