On radial migration of dense regions and objects and local unstability
  of accreting systems
  I have used a newtonian infinite body problem to model a protoplanitary-like
hot accretion disk and added terms of laminar and Stokes friction. Then I used
qualitative methods to show the unstability of local regions leading to a lemma
of radial migration and local unstability in hot, proto-planetary-like
accretion disks. Then I considered a general infinite body problem with a
position dependent, gravitation-like force and a general perturbating term.
