\begin{table}%T4
\par
\caption{\label{orb}Orbital elements of 3 spectroscopic binaries.}
\small%\centering
$$
\begin{tabular}{lr@{.}lr@{.}lr@{.}l}
\hline\hline 
 Element & \multicolumn{2}{c}{He~848} & \multicolumn{2}{c}{He~143} & \multicolumn{2}{c}{He~457} \\
 \hline 
$P$ [d]                     &     89&7734 &     6&1458  &   202&38  \\
                            &      0&0087 &      &0011  &     0&14  \\
$T$ [HJD-2~440~000]           & 45~038&39    & 45~994&781   & 45~868&7  \\
                            &     0&67    &     0&063   &     3&2  \\
$e$                         &     0&180   &     0&095   &     0&327  \\
                            &     0&010   &     0&006   &     0&026  \\
$\gamma$ [km~s$^{-1}$]       &  $-$0&21    &    +5&26    &  $-$3&29  \\
                            &     0&20    &     0&14    &     0&23  \\
$\omega$ [$^{\circ}$]       &    19&2     &   133&4     &   328&1  \\
                            &     2&9     &     4&2     &     5&5  \\
$K_1$ [km s$^{-1}$]         &   29&52     &   31&46     &    11&21  \\
                            &     &54     &     0&20    &     0&30  \\
$K_2$ [km s$^{-1}$]         &   33&53     & \multicolumn{2}{c}{} & \multicolumn{2}{c}{} \\
                            &    0&50     & \multicolumn{2}{c}{} & \multicolumn{2}{c}{} \\             
$f(m)$ [$M_{\odot}$]        &    0&228    &     0&01960  &    0&0250  \\
                            &    0&014    &     0&00041  &    0&0027  \\
$a\sin i$ [Gm]               &   35&85     &     2&646    &   29&5   \\
                            &    0&72     &     0&019    &    1&1   \\
$\sigma ({\rm O{-}C})$ [km~s$^{-1}$] &    1&81     &     0&56     &    1&06  \\
$n_{\rm obs}$ & \multicolumn{2}{c}{41} & \multicolumn{2}{c}{18} & \multicolumn{2}{c}{25} \\
\noalign{\smallskip}
\hline
\end{tabular}
$$ 
\end{table}