The transformation of Spirals into S0 galaxies in the cluster
  environment
  We discuss the observational evidences of the morphological transformation of
Spirals into S0 galaxies in the cluster environment exploiting two big
databases of galaxy clusters: WINGS (0.04 < z < 0.07) and EDisCS (0.4 < z <
0.8). The most important results are: 1) the average number of S0 galaxies in
clusters is almost a factor of $\sim 3 - 4$ larger today than at redshift $z
\sim 1$; 2) the fraction of S0's to Spirals increases on average by a factor
$\sim$ 2 every Gyr; 3) the average rate of transformation for Spirals (not
considering the infall of new galaxies from the cosmic web) is: $\sim$ 5 Sp
into S0's per Gyr and $\sim$ 2 Sp into E's per Gyr; 4) there are evidences that
the interstellar gas of Spirals is stripped by an hot intergalactic medium; 5)
there are also indirect hints that major/minor merging events have played a
role in the transformation of Spiral galaxies. In particular, we show that: 1)
the ratio between the number of S0's and Spirals (NS0/NSp) in the WINGS
clusters is correlated with their X-ray luminosity $L_X$ ; 2) that the
brightest and massive S0's are always close to the cluster center; 3) that the
mean Sersic index of S0's is always larger than that of Spirals (and lower than
E's) for galaxy stellar masses above $10^9.5$ Msun; 4) that the number of E's
in clusters cannot be constant; 5) that the largest difference between the mean
mass of S0's and E's with respect to Spirals is observed in clusters with low
velocity dispersion. Finally, by comparing the properties of the various
morphological types for galaxies in clusters and in the field, we find that the
most significant effect of the environment is the stripping of the outer galaxy
regions, resulting in a systematic difference in effective radius and Sersic
index.
