Galaxy and Mass Assembly (GAMA): Variation in Galaxy Structure Across
  the Green Valley
  Using a sample of 472 local Universe (z<0.06) galaxies in the stellar mass
range 10.25 < log M*/M_sun < 10.75, we explore the variation in galaxy
structure as a function of morphology and galaxy colour. Our sample of galaxies
is sub-divided into red, green and blue colour groups and into elliptical and
non-elliptical (disk-type) morphologies. Using KiDS and VIKING derived postage
stamp images, a group of eight volunteers visually classified bars, rings,
morphological lenses, tidal streams, shells and signs of merger activity for
all systems. We find a significant surplus of rings ($2.3\sigma$) and lenses
($2.9\sigma$) in disk-type galaxies as they transition across the green valley.
Combined, this implies a joint ring/lens green valley surplus significance of
$3.3\sigma$ relative to equivalent disk-types within either the blue cloud or
the red sequence. We recover a bar fraction of ~44% which remains flat with
colour, however, we find that the presence of a bar acts to modulate the
incidence of rings and (to a lesser extent) lenses, with rings in barred
disk-type galaxies more common by ~20-30 percentage points relative to their
unbarred counterparts, regardless of colour. Additionally, green valley
disk-type galaxies with a bar exhibit a significant $3.0\sigma$ surplus of
lenses relative to their blue/red analogues. The existence of such structures
rules out violent transformative events as the primary end-of-life evolutionary
mechanism, with a more passive scenario the favoured candidate for the majority
of galaxies rapidly transitioning across the green valley.
