The Ugly Truth
- The published works on the late stage of Uranus and Neptune formation are wrong.
- The authors of these papers now acknowledge that there were problems with their codes.
- When we attempted to reproduce these, we get very little growth. (Levison & Stewart 2001).
- In Ip 1989 simulation we got one merger in 108 years!
- System got too `hot' to form planets.
- During a simulation, the time to next collision is, .
- As system heats up, and
due to gravitational focusing.
- So, .
System must remain cold to allow growth!
- However, the standard model works for the terrestrial planets! So, what is different?
- Gravitational varies with heliocentric distance, physical
- If objects are close to the Sun then ratio is small.
- If objects are far from the Sun then ratio is large.
- At 20AU scatterings are much more common than collisions, so the system gets excited.