\begin{table}%T6
\caption{\label{table:6}Total mass and number of protoplanets orbiting within, or
crossing, the habitable zone (0.84$-$1.67~AU) at the end of the
\mbox{simulation}.} 
%\centering
\par
\begin{tabular}{c| c c c}
 \hline\hline
Scenario & In & Crossing & Total\\
 \hline
I & 0.18~${M}_{\oplus}$ & 2.13~${M}_{\oplus}$ &
2.31~${M}_{\oplus}$\\
& $N$ = 1 & $N$ = 8 & $N$ = 9\\
II & 0.18~${M}_{\oplus}$ & 1.79~${M}_{\oplus}$ &
1.97~${M}_{\oplus}$\\
& $N$ = 1 & $N$ = 5 & $N$ = 6\\
III & & 1.28~${M}_{\oplus}$ & 1.28~${M}_{\oplus}$\\
& & $N$ = 4 & $N$ = 4\\
IV & 1.17~${M}_{\oplus}$ & 2.00~${M}_{\oplus}$ &
3.17~${M}_{\oplus}$\\
& $N$ = 2 & $N$ = 3 & $N$ = 5\\
V & & 1.34~${M}_{\oplus}$ & 1.34~${M}_{\oplus}$\\
& & $N$ = 1 & $N$ = 1\\
 \hline
\end{tabular}
\end{table}