The relevance of ram pressure stripping for the evolution of blue
  cluster galaxies as seen at optical wavelengths
  Ram pressure stripping is one of the most efficient mechanisms able to affect
the gas reservoir in cluster galaxies and in the last decades many studies have
characterized the properties of stripped galaxies. A definite census of the
importance of this process in local clusters is though still missing. Here we
characterize the fraction of galaxies showing signs of stripping at optical
wavelengths, using the data of 66 clusters from the WINGS and OMEGAWINGS
surveys. We focus on the infalling galaxy population and hence only consider
blue, bright (B<18.2) late-type spectroscopically confirmed cluster members
within 2 virial radii. In addition to "traditional" stripping candidates (SC)
-- i.e. galaxies showing unilateral debris and tails -- we also consider
unwinding galaxies (UG) as potentially stripped galaxies. Recent work has
indeed unveiled a connection between unwinding features and ram pressure
stripping and even though only integral field studies can inform on how often
these features are indeed due to ram pressure, it is important to include them
in the global census. We performed a visual inspection of B-band images and
here we release a catalog of 143 UG. SC and UG each represent ~15-20% of the
inspected sample. If we make the assumption that they both are undergoing ram
pressure stripping, we can conclude that at any given time in the low-z
universe about 35% of the infalling cluster population show signs of stripping
in their morphology at optical wavelengths. These fractions depend on color,
mass, morphology, and little on clustercentric distance. Making some rough
assumptions on the duration of the tail visibility and on the time cluster
galaxies can maintain blue colors, we infer that almost all bright blue
late-type cluster galaxies undergo a stripping phase during their life,
boosting the importance of ram pressure stripping in cluster galaxy evolution.
