\begin{table}%t1
\caption{\label{tab1}Radial velocity dispersion.}
%\centering
\par
\begin{tabular}{ccccc}
\hline\hline\noalign{\smallskip}
Bin   & $N$~stars & $\sigma_{\rm obs}$ & Rotation & $\sigma$\\
\noalign{\smallskip}\hline\noalign{\smallskip}
 30$-$33  & 31 & 6.9 & 3.6 &$7.8 \pm 0.8$\\
 33$-$36  & 18 & 6.6 & 3.4 &$7.4 \pm 1.2$\\
 36$-$40  & 16 & 8.0 & 2.6 &$8.4 \pm 1.2$\\
 40$-$45  & 10 & 7.9 & 1.9 &$8.2 \pm 1.3$\\
\hline
\end{tabular}
\end{table}