\begin{table}%t2
\caption{\label{spectral_indices}Spectral indices.}
\small %\centering
\par
\begin{tabular}{llllll}     
\hline\hline       
 \noalign{\smallskip}                     
Index & H$_2$O   & grav.     & H$_2$O-1   & H$_2$O-2   &  FeH  \\
Value & 1.17     & 1.01      & 0.660      & 0.831      & 0.877  \\
SpT   & L0       & low grav. & L0         & L1.5       & M~8.5   \\
\noalign{\smallskip}        
Index & H$_2$O-A   & H$_2$O-B   & H$_2$O-C   & H$_2$O-D   & \\
Value & 0.593      & 0.724      & 0.733      & 0.817      & \\
SpT   & L2.5       & L3         & L0         & L4         & \\
\hline                  
\end{tabular}
\tablebib{From \citet{a07}; \citet{s04};   and \citet{m03}.}
\vspace*{4mm}
\end{table}