2016MNRAS.458.2962R

Jupiter's core is generally assumed to have formed beyond the snow line. Here we consider an alternative scenario that Jupiter's core may have accumulated in the innermost part of the protoplanetary disc. A growing body of research suggests that small particles ('pebbles') continually drift inward through the disc. If a fraction of drifting pebbles is trapped at the inner edge of the disc, several Earth-mass cores can quickly grow. Subsequently, the core may migrate outward beyond the snow line via planet-disc interactions. Of course, to reach the outer Solar system Jupiter's core must traverse the terrestrial planet-forming region. We use N-body simulations including synthetic forces from an underlying gaseous disc to study how the outward migration of Jupiter's core sculpts the terrestrial zone. If the outward migration is fast (τ_mig ∼ 10⁴ yr), the core simply migrates past resident planetesimals and planetary embryos. However, if its migration is slower (τ_mig ∼ 10⁵ yr) the core clears out solids in the inner disc by shepherding objects in mean motion resonances. In many cases, the disc interior to 0.5-1 au is cleared of embryos and most planetesimals. By generating a mass deficit close to the Sun, the outward migration of Jupiter's core may thus explain the absence of terrestrial planets closer than Mercury. Jupiter's migrating core often stimulates the growth of another large (∼Earth-mass) core - that may provide a seed for Saturn's core - trapped in an exterior resonance. The migrating core also may transport a fraction of terrestrial planetesimals, such as the putative parent bodies of iron meteorites, to the asteroid belt.