\begin{table}%t6
%\centering
\par
  \caption{\label{tab6}The new system parameters.}
  $$
    \begin{tabular}{c@{\dotfill}cr@{~$\pm$~}lr@{~$\pm$~}lr@{~$\pm$~}l}
  \hline\hline
    \hspace{1cm}Parameter\hspace{1cm} &
    &
    \multicolumn{2}{c}{WASP-2}&
    \multicolumn{2}{c}{TrES-2}&
    \multicolumn{2}{c}{TrES-4}\\[0.5ex]
  \hline
    $R_{\rm p}/R_*$           & & 0.1332&0.0015 & 0.1279&0.0010 & 0.1000&0.0009\\
    $a/R_*$                      & &   8.01&$^{0.32}_{0.2}$&   7.65&0.12   &   6.05&0.13  \\
    $b$                          & &  0.725&0.026  &  0.851&0.006  &  0.752&0.015 \\
    $i$ $({\rm deg})$         & &  84.80&0.39   &  83.62&0.14   &  82.86&0.33  \\
    $\rho_*$ $({\rm g/cm^3})$ & &  2.095&0.205  &  1.390&0.060  &  0.333&0.022 \\
    $\log g_{\rm p}$          & &  3.279&0.036  &  3.284&0.016  &  2.867&0.038 \\
    $R_*/R_\odot$                & &  0.843&0.063  &  0.999&0.033  &  1.809&0.064 \\
    $R_{\rm p}/R_{\rm Jup}$& &  1.117&0.082  &  1.272&0.041  &  1.799&0.063 \\
    $M_{\rm p}/M_{\rm Jup}$& &  0.914&0.092  &  1.199&0.052  &  0.919&0.073 \\
    $\rho_{\rm p}$ $({\rm g/cm^3})$& &   0.87&0.24   &   0.77&0.09   &  0.209&0.029 \\
    $\Theta$                     & & 0.0590&0.0044 & 0.0697&0.0022 & 0.0381&0.0030\\
    $T_{\rm eq}$ $({\rm K})$& &   1300&54     &   1495&17     &   1782&29    \\
    $a$ $({\rm AU})$          & &0.03138&0.00142&0.03556&0.00075&0.05091&0.00071\\[0.5ex]
  \hline
  \end{tabular}
  $$
\end{table}