\begin{table}%t8
\caption{Binary systems parameters for the 6~binaries in the $\sigma$~Ori cluster for which a sinusoidal fit  of the RV curves was performed. Errors are~$1\sigma$.}\label{tab:bin} 
%\centerline
 {\small 
\begin{tabular}{lrrccrrcc}
\hline\hline\noalign{\smallskip}
ID& $V_\circ^{a}$ (km~s$^{-1}$)& $P^{b}$ (days)& $K_1^{c}$ (km~s$^{-1}$)& 
$K_2^{c}$ (km~s$^{-1}$)& $a_1 \sin i^{d}$ ($R_\odot$)& $a_2 \sin i^{d}$ ($R_\odot$)& $f(M)^{e}$ ($M_\odot$)& $M_1/M_2^{f}$ \\
\noalign{\smallskip}\hline\noalign{\smallskip}
\object{S29}&     $32.06 \pm 0.73$  &  $8.72  \pm 0.02 $ & $25.4 \pm 1.3$ & $41.7 \pm 1.3$& 
 $4.38 \pm 0.22$ &  $7.18 \pm 0.22$ &   $0.015 \pm 0.002$ & $1.64 \pm 0.10$ \\
\object{S53}&  $30.61 \pm 1.06$  &  $8.52 \pm 0.01$ & $29.1 \pm 2.8$ & $32.1 \pm 2.3$& 
$ 4.90 \pm 0.46$ &  $5.39 \pm 0.39$ & $0.022 \pm 0.006$ & $1.10 \pm 0.13$\\
\object{S84}&  $23.43 \pm 0.69$  &  $6.07 \pm 0.01$ & $43.8 \pm 1.3$& $43.8 \pm 1.3$& 
 $5.25 \pm 0.16$&  $5.25 \pm 0.16$& $0.053 \pm 0.005$& $1.00 \pm 0.04$\\
\object{S85}&  $72.34 \pm 0.88$  & $12.78 \pm 0.02$ & $35.3 \pm 2.3$& $43.0 \pm 2.3$& 
 $8.91 \pm 0.59$& $10.84 \pm 0.59$& $0.058 \pm 0.012$& $1.22 \pm 0.10$\\
\object{S89}&  $16.54 \pm 2.02$  & $13.82 \pm 0.04$ & $69.8 \pm 4.4$& $86.5 \pm 4.4$& 
$19.02 \pm 1.19$& $23.59 \pm 1.20$& $0.486 \pm 0.092$& $1.24 \pm 0.10$\\
\object{S96}& $-$$34.79 \pm 1.19$& $3.895 \pm 0.004$& $43.4 \pm 1.6$& \ldots& 
 $3.33\pm 0.12$& \multicolumn{1}{c}{\ldots}& $0.033 \pm 0.004$& \ldots \\
\hline
\end{tabular}}
\medskip
$^a$~Velocity of the binary system center of mass; $^b$~period of the binary system; $^c$~semi-amplitude of the RV curve; $^d$~semi-major axis of the binary orbit; $^e$~binary system mass function; $^f$~mass ratio of the binary components.
\end{table}