\begin{table}%T3
\caption{ \label{table:times2} Comparison of formation times and core 
masses for several disc densities with a planetesimal radius of 10~km.}
%\centering
\small
\begin{tabular}{l p{1.3 cm} p{1 cm} p{1.3 cm} p{1 cm}}
\hline\hline
Disc density & \multicolumn{2}{c}{Without gas drag} &  \multicolumn{2}{c}{With gas
 drag}\\
\cline{2-5}
 [MMSN]& Formation time [My] & Core mass [${M_{\oplus}}$] & 
 Formation time [My] & Core mass [${M_{\oplus}}$]\\
\hline
%\\
$\; \; 6$   & 9   & 34  & 5.6  & $\; \; 69$ \\
$\; \; 7$   & 7   & 40  & 4    & $\; \; 80$ \\
$\; \; 8$   & 6   & 45  & 3    & $\; \; 92$ \\
$\; \; 9$   & 4.8 & 50  & 2.2  &  104 \\
10  & 4   & 55  & 1.75 & 115 \\
\hline 
\end{tabular}
\end{table}