\begin{table}%t6
\small
\caption{\label{table:144}Average [X/H] abundance, corresponding standard deviation, and average number of lines used for abundances determination.}             % title of Table      % is used to refer this table in the text
%%\centering

                          % used for centering table
\begin{tabular}{c c c c}        % centered columns (4 columns)
\hline\hline                 % inserts double horizontal lines
\par
Species   &	$\langle$[X/H]$\rangle$    & $\sigma$ & $\langle N\rangle$ \\  % table heading 
\hline                                                 % inserts single horizontal line
Si        &	--0.11	   &	0.1 & 8.4 \\ 
Ni        & 	0.01	   &	0.10 & 23.3\\
\hline  
\end{tabular} 
\end{table}