Rapid collisional evolution of comets during the formation of the Oort cloud

摘要: The Oort cloud1 of comets was formed by the ejection icy planetesimals from region giant planets—Jupiter, Saturn, Uranus and Neptune—during their formation2. Dynamical simulations3,4 have previously shown that reach cloud only after being perturbed into eccentric orbits result in close encounters with planets, which then eject them to distant about 104 105 AU Sun (1 AU is average Earth–Sun distance). All models constructed until now simulate formation using gravitational effects; these include influence Sun, planets external perturbers such as passing stars Galactic tides. Here we show physical collisions between small debris play a fundamental hitherto unexplored role throughout most process. For standard protosolar nebula (starting minimum-mass nebula) find collisional evolution so severe erosional lifetimes are much shorter than timescale for dynamical ejection. It therefore appears will prevent escaping locations disk mass there declines sufficiently lifetime. One consequence total may be less currently believed.