Building the peanut: simulations and observations of peanut-shaped
  structures and ansae in face-on disk galaxies
  (X/peanut)-shaped features observed in a significant fraction of disk
galaxies are thought to have formed from vertically buckled bars. Despite being
three dimensional structures, they are preferentially detected in near edge-on
projection. Only a few galaxies are found to have displayed such structures
when their disks are relatively face-on - suggesting that either they are
generally weak in face-on projection or many may be hidden by the light of
their galaxy's face-on disk.
  Here we report on three (collisionless) simulated galaxies displaying
peanut-shaped structures when their disks are seen both face-on and edge-on -
resembling a three-dimensional peanut or dumbbell. Furthermore, these
structures are accompanied by ansae and an outer ring at the end of the bar ---
as seen in real galaxies such as IC~5240.
  The same set of quantitative parameters used to measure peanut structures in
real galaxies have been determined for the simulated galaxies, and a broad
agreement is found. In addition, the peanut length grows in tandem with the
bar, and is a maximum at half the length of the bar. Beyond the cutoff of these
peanut structures, towards the end of the bar, we discover a new
positive/negative feature in the $B_6$ radial profile associated with the
isophotes of the ansae/ring.
  Our simulated, self-gravitating, three-dimensional peanut structures display
cylindrical rotation even in the near-face-on disk projection. In addition, we
report on a kinematic pinch in the velocity map along the bar minor-axis,
matching that seen in the surface density map.
