Kevin J. Walsh, Alessando Morbidelli, Sean N. Raymond, David P. O'Brien, Avi M. Mandell
Jupiter and Saturn formed in a few million years (Haisch et al. 2001) from a
gas-dominated protoplanetary disk, and were susceptible to gas-driven migration
of their orbits on timescales of only ~100,000 years (Armitage 2007).
Hydrodynamic simulations show that these giant planets can undergo a two-stage,
inward-then-outward, migration (Masset & Snellgrove 2001, Morbidelli & Crida
2007, Pierens & Nelson 2008). The terrestrial planets finished accreting much
later (Klein et al. 2009), and their characteristics, including Mars' small
mass, are best reproduced by starting from a planetesimal disk with an outer
edge at about one astronomical unit from the Sun (Wetherill 1978, Hansen 2009)
(1 AU is the Earth-Sun distance). Here we report simulations of the early Solar
System that show how the inward migration of Jupiter to 1.5 AU, and its
subsequent outward migration, lead to a planetesimal disk truncated at 1 AU;
the terrestrial planets then form from this disk over the next 30-50 million
years, with an Earth/Mars mass ratio consistent with observations. Scattering
by Jupiter initially empties but then repopulates the asteroid belt, with
inner-belt bodies originating between 1 and 3 AU and outer-belt bodies
originating between and beyond the giant planets. This explains the significant
compositional differences across the asteroid belt. The key aspect missing from
previous models of terrestrial planet formation is the substantial radial
migration of the giant planets, which suggests that their behaviour is more
similar to that inferred for extrasolar planets than previously thought.
View original:
http://arxiv.org/abs/1201.5177
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