\begin{table}%t2
    \caption{Star formation regions of potential triggered origins.}
    \label{other regions}
    %\begin{center}
\par
    \begin{tabular}{cccccc}
     \hline
     \hline
\par
     Cloud      &  Spectral type of & Projected distance from &
     Estimated shock &  &
     Evidence of triggered \\
     & main ionizing star & ionizing star &
     velocity & & star formation \\
     \hline\noalign{\smallskip}
     Molecular pillars in M16$^1$  &  O5V  & 2 pc  & 1.3 ${\rm km~s^{-1}}$ &
     & age gradient of YSOs \\
\par
     IC1396N$^2$  &  O6.5f & 11 pc & 0.6 ${\rm km~s^{-1}}$& &
     age gradient of YSOs \\
\par
     SFO11, SFO11NE, SFO11E$^3$  &   O6V  & 11 pc & 1.4 ${\rm km~s^{-1}}$&
     & on-going star formation\\
     & & &  & & near ionization front  \\
\par
     Orion bright-rimmed clouds$^4$  & O8III$^a$ or O6:$^b$  & -- &  --   &
     & on-going star formation \\
     & & &  & & near ionization front  \\
\par
     \hline
    \end{tabular}
     %\end{center}
\par
    $^a$  Ionizing star of B30 and B35.  $^b$  Ionizing star of IC2118, LDN1616, and LDN1634. \\
    References: (1) \citet{2002ApJ...568L.127F};
    \citet{1999AetA...342..233W}; (2) \citet{2007ApJ...654..316G}; (3)
    \citet{2004AetA...414.1017T}; (4) \citet{2005ApJ...624..808L}.
   \end{table}