\begin{table}%t2
\par
     \caption{\label{orbite}Orbital parameters.}
       %\centerline
 {
     \begin{tabular}{ccccc}
       \hline\hline
       Orbit id & $r_{\rm ini}$ &  $v_{\rm ini}$ & $L^{{a}}$  & $E^{{b}}$ \\
         & [kpc] & [100 $\rm km~s^{-1}$] &  [$10^2~\rm km~s^{-1}~kpc$] &  [$10^4~ \rm km^2~s^{-2}$]\\
       \hline
       01& 100.& 2.0&57.0&0.\\
       02& 100.& 3.0&59.0.&2.5\\
       05& 100.& 2.0&80.0&0.\\
       13& 100.& 0.0&0.0&--2.\\
       14& 70.0& 1.5&41.3&--0.66\\
       15& 70.0& 1.6&41.3&--1.57\\       
       \hline  
     \end{tabular}}
\par
     \smallskip
$^{{a}}$ It is the absolute value of the angular momentum of the unit mass, i.e., $L=\mid
\vec{r} \times \vec{v}\mid $.
 $^{{b}}$  It is the total energy of the relative motion,  i.e.,  $E={v}^2/2-G(m_1+m_2)/r$, with $m_1=m_2=2.3 \times10^{11}~M_{\odot}$.
   \end{table}