The effect of an early planetesimal-driven migration of the giant planets on terrestrial planet formation

Abstract

The migration of the giant planets due to the scattering of planetesimals causes powerful resonances to move through the asteroid belt and the terrestrial planet region. Exactly when and how the giant planets migrated is not well known. In this paper we present results of an investigation of the formation of the terrestrial planets during and after the migration of the giant planets. The latter is assumed to have occurred immediately after the dissipation of the nebular disk -i.e. "early" with respect to the timing of the late heavy bombardment (LHB). The presumed cause of our modeled early migration of the giant planets is angular mometum transfer between the planets and scattered planetesimals. Our model forms the terrestrial planets from a disk of material which stretchs from 0.3-4.0 AU, evenly split in mass between planetesimals and planetary embryos. Jupiter and Saturn are initially at 5.4 and 8.7 AU respectively, on orbits with eccentricities comparable to the current ones, and migrate to 5.2 and 9.4 AU with an e-folding time of 5 Myr. Unfortunately, the terrestrial planets formed in the simulations are not good analogs for the current solar system, with Mars typically being much too massive. Moreover, the final distribution of the planetesimals remaining in the asteroid belt is inconsistent with the observed distribution of asteroids. This argues that, even if giant planet migration had occurred early, the real evolution of the giant planets would have to have been of the "jumping-Jupiter" type, i.e. the increase in orbital separation between Jupiter and Saturn had to be dominated by encounters between Jupiter and a third, Neptune-mass planet. This result was already demonstrated for late migrations occuring at the LHB time by previous work, and this paper shows those conclusions hold for early migration as well.

Vesta and Ceres: Crossing the History of the Solar System

“…However, Morbidelli et al (2010) argued that the migration rate assumed by Minton and Malhotra (2010) are too fast for such kind of scenario and that more realistic migration rates fail to reproduce orbital structures compatible with that of the Main Asteroid Belt. Similar results are obtained by Walsh and Morbidelli (2011) in exploring the effects of a possible early planetesimal-driven migration of the giant planets. According to Morbidelli et al (2010), the observational constrains can be better reproduced either if the migration followed a path similar to the one described in the Nice Model or an even more drastic "Jumping Jupiters" migration pattern like those proposed to explain the peculiar orbital structures of several multi-planet extrasolar systems (Weidenschilling and Marzari 1996).…”

Chemical Composition of Comet C/2007 N3 (Lulin): Another ‘‘Atypical’’ Comet

“…The standard model of cometary origins suggests that most cometary nuclei now residing in the Kuiper Disk formed in our planetary system at distances beyond ∼5 AU, though the "Grand Tack" model (Walsh & Morbidelli 2011) suggests that many might have originated in the terrestrial planets region. Whether Oort Cloud comets formed solely in our planetary system or were also captured from neighboring stars in the Sun's birth cluster (Levison et al 2010) is also in play.…”

MAIN BELT ASTEROIDS WITHWISE/NEOWISE. I. PRELIMINARY ALBEDOS AND DIAMETERS

“…Although the current understanding of the history of the Main Belt has the asteroids forming in or near their current locations, new theories are being proposed that the Main Belt may in fact be the result of a mixing of two distinct populations from different regions of the Solar system. Migrations of the giant planets may have both cleared many of the objects that initially formed in the Main Belt region and repopulated this area with objects from beyond the "snow line" (Morbidelli et al 2010;Walsh & Morbidelli 2011). We then might expect the Main Belt to be composed of two overlapping populations, one having formed in a volatile-poor region of the protosolar disk and one forming in a volatile rich area, though the latter population would lose any surface volatiles over the age of the Solar system.…”