The partitioning of the inner and outer solar system by a structured protoplanetary disk

Abstract

<p>Mass-independent isotopic anomalies in planets and meteorites define two cosmochemically distinct regions: the carbonaceous and non-carbonaceous meteorites, implying that the non-carbonaceous (terrestrial) and carbonaceous (jovian) reservoirs were kept separate during and after planet formation. The iron meteorites show a similar dichotomy.</p><p>The formation of Jupiter is widely invoked to explain this compositional dichotomy by acting as an effective barrier between the two reservoirs. Jupiter’s solid kernel possibly grew to ~20 Mearth in ~1 Myr from the accretion of sub meter-sized objects (termed “pebbles”), followed by slower accretion via planetesimals. Subsequent gas envelope contraction is thought to have led to Jupiter’s formation as a gas giant.</p><p>We show using dynamical simulations that the growth of Jupiter from pebble accretion is not fast enough to be responsible for the inferred separation of the terrestrial and jovian reservoirs. We propose instead that the dichotomy was caused by a pressure maximum in the disk near Jupiter’s location, which created a ringed structure such as those detected by the Atacama Large Millimeter/submillimeter Array(ALMA). One or multiple such long-lived pressure maxima almost completely prevented pebbles from the jovian region reaching the terrestrial zone, maintaining a compositional partition between the two regions. We thus suggest that our young solar system’s protoplanetary disk developed at least one and likely multiple rings, which potentially triggered the formation of the giant planets [1].</p><p><br>[1] Brasser, R. and Mojzsis, S.J. (2020) Nature Astronomy doi: 10.1038/s41550-019-0978-6</p>