\begin{table}%t1
\caption{\label{tbl-shockmods}Shock models.}             
%\centering
\par
\begin{tabular}{l c c c c c c c c c c}        
\hline\hline\noalign{\smallskip}                
Model & $v_{\rm shock}$ (km s$^{-1}$) & $n_{\rm H,0}$ (cm$^{-3}$) & $X_{\rm H_2,0}$ & $t_{\rm disc}$\tablefootmark{1}  (yr) & $n_{\rm H,disc}$\tablefootmark{1} (cm$^{-3}$) & $T_{\rm g,disc}$\tablefootmark{1} (K) &  $t_{\rm 2}$\tablefootmark{2} (yr) & $n_{\rm H,2}$\tablefootmark{2} (cm$^{-3}$) & $T_{\rm g,2}$\tablefootmark{2} (K) & size\tablefootmark{2} (pc)\\ 
\hline\noalign{\smallskip}                        
1 & 20 & 1 & 0    & 1.2(+06)\tablefootmark{3} & 2.7(+03) & 21.8 &  6.0(+07)    &  5.7(+03) & 10.7 & 0.21\\    
2 & 30 & 1 & 0    & 2.5(+05)     & 6.7(+03) & 20.5 &  4.1(+07)    &  9.5(+03) & 14.3 & 0.13\\    
3 & 10 & 3 & 0.25 & 4.4(+05)     & 1.9(+03) & 25.9 &  4.2(+07)    &  3.7(+03) & 13.7 & 0.52 \\ 
4 & 15 & 10 & 0   & 1.2(+05)     & 1.7(+04) & 20.9 &  8.4(+06)    &  2.4(+04) & 14.6 & 0.05 \\   
\hline                                   
\end{tabular}
\tablefoot{\tablefoottext{1} \textrm{Refers} to values at discontinuity.  See, e.g., Fig.~\ref{Evolvehydro}. 
\tablefoottext{2} \textrm{Refers} to values at $A_{\rm V}\approx 2$. 
\tablefoottext{3} {$a(b) = a \times 10^{b}$}.} 
\end{table}