\begin{table}%t2
%\centering
\par
\caption{\label{formation}Formation temperatures of various emission lines.}  
\begin{tabular}{ccc}
\hline\hline\noalign{\smallskip}
Ion & Wavelength [\AA]  & Formation temperature [K]  \\
\hline
\ion{Fe}{i} &7068.42  &  3300--4500 (3900) \\
\ion{Fe}{i} &7748.28  &  3600--4500 (4200) \\
\ion{K}{i}  &7698.98  &  4200--5100 (4600) \\
\ion{Ca}{ii}&8498.02  &  8500--10~900 (8500) \\
\ion{He}{i} & 6678.15 &  8500--25~200 \\
\ion{He}{i} &7065.19  &  8500--25~000 \\
\ion{H}{i}  &6562.82  &  8500--12~000 (8500)\\
\ion{H}{i}  &10049.38 &  8500--15~700 (8500)\\
\ion{H}{i}  &3711.97 &  8000--15~300 (9100)\\
\ion{H}{i}  &3703.86 &  8000-15~300 (9200)\\
\ion{O}{i}  & 7771.96, 7774.18,7775.40  & 9000--13~200 (10~900) \\
\ion{Fe}{ii}& 3226.81 & 8000--14~200 (11~700)\\ 
\hline
\end{tabular}
\vspace*{4mm}
\end{table}