From blue star-forming to red passive: galaxies in transition in
  different environments
  Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0.11 drawn
from the Padova Millennium Galaxy Group Catalog (PM2GC), we use the (U-B)_rf
color and morphologies to characterize galaxies, in particular those that show
signs of an ongoing or recent transformation of their star formation activity
and/or morphology - green galaxies, red passive late types, and blue
star-forming early types. Color fractions depend on mass and only for
M_*<10^(10.7)M_sun on environment. The incidence of red galaxies increases with
increasing mass, and, for M_*<10^(10.7)M_sun, decreases toward the group
outskirts and in binary and single galaxies. The relative abundance of green
and blue galaxies is independent of environment, and increases monotonically
with galaxy mass. We also inspect galaxy structural parameters, star-formation
properties, histories and ages and propose an evolutionary scenario for the
different subpopulations. Color transformations are due to a reduction and
suppression of SFR in both bulges and disks which does not noticeably affect
galaxy structure. Morphological transitions are linked to an enhanced
bulge-to-disk ratio due to the removal of the disk, not to an increase of the
bulge. Our modeling suggests that green colors might be due to star formation
histories declining with long timescales, as an alternative scenario to the
classical "quenching" processes. Our results suggest that galaxy
transformations in star formation activity and morphology depend neither on
environment nor on being a satellite or the most massive galaxy of a halo. The
only environmental dependence we find is the higher fast quenching efficiency
in groups giving origin to post-starburst signatures.
