Why the Milky Way's bulge is not only a bar formed from a cold thin disk
  By analyzing a N-body simulation of a bulge formed simply via a bar
instability mechanism operating on a kinematically cold stellar disk, and by
comparing the results of this analysis with the structural and kinematic
properties of the main stellar populations of the Milky Way bulge, we conclude
that the bulge of our Galaxy is not a pure stellar bar formed from a
pre-existing thin stellar disk, as some studies have recently suggested. On the
basis of several arguments emphasized in this paper, we propose that the bulge
population which, in the Milky Way, is observed not to be part of the peanut
structure corresponds to the old galactic thick disk, thus implying that the
Milky Way is a pure thin+thick disk galaxy, with only a possible limited
contribution of a classical bulge.
