Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-05-11
Ann.Rev.Astron.Astrophys. 42 (2004) 549-601
Astronomy and Astrophysics
Astrophysics
to appear in ARA&A (2004), 51 pages, 3 figures
Scientific paper
10.1146/annurev.astro.42.053102.
Planets form in the circumstellar disks of young stars. We review the basic physical processes by which solid bodies accrete each other and alter each others' random velocities, and we provide order-of-magnitude derivations for the rates of these processes. We discuss and exercise the two-groups approximation, a simple yet powerful technique for solving the evolution equations for protoplanet growth. We describe orderly, runaway, neutral, and oligarchic growth. We also delineate the conditions under which each occurs. We refute a popular misconception by showing that the outer planets formed quickly by accreting small bodies. Then we address the final stages of planet formation. Oligarchy ends when the surface density of the oligarchs becomes comparable to that of the small bodies. Dynamical friction is no longer able to balance viscous stirring and the oligarchs' random velocities increase. In the inner-planet system, oligarchs collide and coalesce. In the outer-planet system, some of the oligarchs are ejected. In both the inner- and outer-planet systems, this stage ends once the number of big bodies has been reduced to the point that their mutual interactions no longer produce large-scale chaos. Subsequently, dynamical friction by the residual small bodies circularizes and flattens their orbits. The final stage of planet formation involves the clean up of the residual small bodies. Clean up has been poorly explored.
Goldreich Peter
Lithwick Yoram
Sari Re'em
No associations
LandOfFree
Planet Formation by Coagulation: A Focus on Uranus and Neptune does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Planet Formation by Coagulation: A Focus on Uranus and Neptune, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Planet Formation by Coagulation: A Focus on Uranus and Neptune will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-535691