\begin{table}%t4
  %%\centering

\par
  \caption{Three sets of planet masses used in numerical integrations}
  \label{tab: planetmasses}
  \begin{tabular}{lccc} \hline\hline
    HR~8799        & b & c & d \\
    \hline
    low mass      & $5M_{\rm Jup}$  & $ 7M_{\rm Jup}$ & $7M_{\rm Jup}$
\\
    nominal mass  & $7M_{\rm Jup}$  & $10M_{\rm Jup}$ & $10M_{\rm Jup}$
\\
    high mass     & $11M_{\rm Jup}$ & $13M_{\rm Jup}$ & $13M_{\rm Jup}$
\\
    \hline
  \end{tabular}
\end{table}