Can drag keep the system cold enough to allow accretion?

• Tried two types of drag: To simulate
  • Interactions with small particles.
  • Interactions with waves in Solar Nebula.
    • From Ward (1993).
• Needed about 400 gm/cm² at 5AU to get planets to form.
  • About the mass of the Solar Nebula.
  • If correct, we can rule out interactions with comets.
• Planets only form close to Saturn.
  • Due to radial migration of drag.

If True, Uranus and Neptune Formed Early.

• But, how did they get to their current semi-major axes?