Simulataneous formation of giant planets

ANDREA FORTIER; OCTAVIO MIGUEL GUILERA; YANN ALIBERT; ADRIÁN BRUNINI; OMAR GUSTAVO BENVENUTO

Ringberg

Workshop; Ringberg Workshop, Planetary Population Synthesis: the predictive power of planet formation theory; 2010

Max Planck Institute of Astronomy

The so-called Nice model suggests that the initial orbital configuration of the giant planets was much more compact than the one we observe today. The success of this model lies on the fact that it is able to reproduce the main observational constraints of the present orbital structure of the outer solar system, that was achieved after the migration of the fully formed giant planets to their present location. Here we explore some necessary conditions for the simultaneous formation of the giant planets in line with the initial configuration proposed by the Nice model. We compute our model in the framework of the core instability hypothesis, adopting the oligarchic growth regime for the core. Accreted planetesimals are considered to follow a size distribution. We show that steep surface density profiles, like  a-2 as proposed by Desch (2007), do not favor the simultaneous formation of solar system giant planets. On the other hand, smoother surface density profiles (as, for example,  a-1, also supported by observations of circumstellar disks around young stars), where planetesimal migration plays an important role, favor the simultaneous formation. We find that, for this kind of profiles, the formation timescale of the giant planets are in agreement with the estimates of disk lifetimes when a significant mass of the solids accreted by the planets is contained in small planetesimals.