\begin{table}%t7
\caption{Comparison of average values of colour gradients for our full sample and 
for the $Pec$ subsample of morphologically peculiar objects (Michard \& Prugniel 
\cite{Michard04}). Among $Pec$ objects we distinguish the $YP$ family with evidence for the 
presence of some young stars and the $NP$~family with no such evidence.
\label{tab7}}
%\centerline
{\begin{tabular}{llllllllll}
\hline    \hline    
  Y          &$All$& $N$ &$A\rm v$ &$YP$ & $N$ & $A\rm v$& $NP$& $N$ & $A\rm v$  \\
  \hline
$\Delta_{BV}$&$All$& 53&--$0.066\pm.003$&$YP$& 9&$-0.060\pm.005$&$NP$&7&$-0.057\pm.006$\\
$\Delta_{UB}$& id & 41&--$0.157\pm.007$& id & 7&$-0.137\pm.006$& id &6&$-0.138\pm.010$\\
$\Delta_{BR}$& id & 43&--$0.082\pm.004$& id & 8&$-0.074\pm.005$& id &6&$-0.074\pm.011$\\
$\Delta_{VI}$& id & 47&--$0.061\pm.005$& id & 7&$-0.052\pm.006$& id &7&$-0.053\pm.008$\\
$\Delta_{VJ}$& id & 53&--$0.136\pm.013$& id & 9&$-0.108\pm.029$& id &7&$-0.123\pm.021$\\
$\Delta_{VK}$& id & 53&--$0.227\pm.015$& id & 9&$-0.169\pm.029$& id &7&$-0.201\pm.024$\\
$\Delta_{JK}$& id & 54&--$0.093\pm.004$& id & 9&$-0.073\pm.009$& id &7&$-0.083\pm.009$\\
\hline
\end{tabular}}
\par
\smallskip
(1) Gradient $Y$; (2) sample; (3) number of objects $N$; (4) average with estimated error;
(5) sample; (6) number of objects $N$; (7) average with estimated error;
(8) sample; (9) number of objects $N$; (10) average with estimated error.
\end{table}