Polar Disk Galaxies as new way to study galaxy formation: the case of
  NGC4650A
  NGC4650A is a polar disk galaxy: this is a peculiar object composed by a
central spheroidal component, the host galaxy (HG), and an extended disk made
up by gas, stars and dust, which orbits nearly perpendicular to the plane of
the central galaxy. The existence of two decoupled components of the angular
momentum let this object the ideal laboratory i) to study gravitational
interactions and merging and ii) to constrain the 3D shape of its dark matter
halo. In view of these applications, I will present two ongoing projects which
aim to constrain i) the formation scenario for polar disks and ii) the dark
halo content and shape, through a detailed analysis of the observed structure,
metallicity and dynamics of NGC4650A.
