Formation of Planetesimals and Accretion of the Terrestrial Planets |
| |
Authors: | Stuart J Weidenschilling |
| |
Institution: | (1) Planetary Science Institute, Tucson, AZ 85705, USA |
| |
Abstract: | Planetesimals formed in the solar nebula by collisional coagulation. Dust aggregates settled toward the central plane, the
larger ones growing by sweeping up smaller ones. A thin, dense layer of particles formed; shear-generated turbulence and differential
motions induced by gas drag inhibited gravitational instability. Growth proceeded by collisions, producing planetesimals on
a timescale of a few thousand years in the terrestrial zone. For bodies smaller than about a kilometer, motions were dominated
by gas drag, and impact velocities decreased with size. At larger sizes gravitational interactions became significant, and
velocities increased due to mutual perturbations. Larger bodies then grew more rapidly, this ``runaway' led to formation
of tens to hundreds of lunar- to Mars-sized planetary embryos in the zone of terrestrial planets. The final accretion of these
bodies into a few planets involved large impacts, and occurred on a timescale of 107 to 108 years. This scenario gives a reasonably consistent picture of the origin of the terrestrial planets, but does not account
for the anomalously low eccentricities of the Earth and Venus.
This revised version was published online in June 2006 with corrections to the Cover Date. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|