Forming the cores of giant planets from the radial pebble flux in protoplanetary discs

By Michiel Lambrechts, Anders Johansen. 2014

280 citations recorded by the source corpus.

The formation of planetary cores must proceed rapidly in order for the giant planets to accrete their gaseous envelopes before the dissipation of the protoplanetary gas disc (less than or similar to 3 Myr). In orbits beyond 10 AU, direct accumulation of planetesimals by the cores is too slow. Fragments of planetesimals could be accreted faster, but planetesimals are likely too large for fragmentation to be efficient, and resonant trapping poses an additional hurdle. Here we instead investigate the accretion of small pebbles (mm-cm sizes) that are the natural outcome of an equilibrium between the growth and radial drift of particles. We construct a simplified analytical model of dust coagulation and pebble drift in the outer disc, between 5 AU and 100 AU, which gives the temporal evolution of the solid surface density and the dominant particle size. These two key quantities determine how core growth proceeds at various orbital distances. We find that pebble surface densities are sufficiently high to achieve the inside-out formation of planetary cores within the disc lifetime. The overall efficiency by which dust gets converted to planets can be high, close to 50% for planetary architectures similar to the solar system. Growth by pebble accretion in the outer disc is sufficiently fast to overcome catastrophic type I migration of the cores. These results require protoplanetary discs with large radial extent (greater than or similar to 100 AU) and assume a low number of initial seed embryos. Our findings imply that protoplanetary discs with low disc masses, as expected around low-mass stars (<1 M-circle dot), or with sub-solar dust-to-gas ratios, do not easily form gas-giant planets (M greater than or similar to 100 M-E), but preferentially form Neptune-mass planets or smaller (M less than or similar to 10 M-E). This is consistent with exoplanet surveys which show that gas giants are relatively uncommon around stars of low mass or low metallicity. (Less)

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1e8455e8b7a1707158443932415cf117288c497d

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Citations in the corpus

Planetesimal formation starts at the snow line (2017, unknown): “The radial dependence of sizes and radial flux of pebbles that we can extract from our results are important parameters of the pebble accretion models (Ormel & Klahr 2010; Lambrechts & Johansen 2014; Levison et al. 2015; Visser & Ormel 2016).”
Close-in planetesimal formation by pile-up of drifting pebbles (2016, background): “The same effect was also described by Lambrechts & Johansen (2014), who called it a “pebble formation front”.”
Separating gas-giant and ice-giant planets by halting pebble accretion (2014, background): “A more thorough discussion of core growth can be found in Lambrechts & Johansen (2014), where we investigate embryo growth in a global model that includes dust growth and the drift of pebbles.”
The great dichotomy of the Solar System: Small terrestrial embryos and massive giant planet cores (2015, methodology): “Growth of embryos and cores by pebble accretion In a series of recent papers (Lambrechts & Johansen, 2012, 2014; Ormel and Klahr, 2010; Johansen and Lacerda, 2010; Murray-Clay et al., 2011; Morbidelli and Nesvorny, 2012; Kretke and Levison, 2014b), a new model has been proposed in which…”
Chemical enrichment of giant planets and discs due to pebble drift (2017, methodology): “However, since the Lambrechts & Johansen (2014) model is also based upon insights from grain growth models, such as the Birnstiel et al. (2012) model that we use, we do not expect the differences to be too great.”
Planetesimal formation near the snowline: in or out? (2017, background): “After planetesimals of a certain size have formed, they can subsequently accrete pebbles and quickly grow to larger bodies (e.g., Ormel & Klahr 2010; Lambrechts & Johansen 2012, 2014; Bitsch et al. 2015; Visser & Ormel 2016).”
IN SITU FORMATION AND DYNAMICAL EVOLUTION OF HOT JUPITER SYSTEMS (2015, background): “Rapid conversion of planetesimals into SuperEarths by accretion of pebbles appears to be fully consistent with the envisioned evolutionary sequence (Lambrechts and Johansen 2012, 2014; Levison et al. 2015).”
Dust Evolution and the Formation of Planetesimals (2016, background): “With growth and drift providing a constant supply of inward drifting grains of the right sizes to be accreted, the growth time scale of cores, particularly in the outer regions of disks can be reduced significantly Lambrechts & Johansen (2012, 2014).”
The Non-carbonaceous–Carbonaceous Meteorite Dichotomy (2020, background): “This would probably require formation of Jupiter’s core by pebble accretion (Lambrechts and Johansen 2014; Levison et al. 2015).”
The structure of protoplanetary discs around evolving young stars (2014, background): “Such late formation of planetesimals in the outer disc could explain why Neptune and Uranus did not grow to become gas giants (Lambrechts et al. 2014; Lambrechts & Johansen 2014).”
Formation of planetary systems by pebble accretion and migration (2018, methodology): “Due to this “pebble filtering”, the inner bodies see a reduced pebble flux (Lambrechts & Johansen 2014; Guillot et al. 2014; Morbidelli et al. 2015).”
Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants (2018, methodology): “Typically, the pebbles accreted by planets in our model have Stokes numbers in the range of 0.05 < τf < 0.4, as those are the Stokes numbers of the pebbles dominated by radial drift (Birnstiel et al. 2012; Lambrechts & Johansen 2014).”
Origin of water in the inner Solar System: Planetesimals scattered inward during Jupiter and Saturn's rapid gas accretion (2017, background): “In contrast, the pebble accretion model proposes that giant planet cores grow preferentially by the accretion of small pebbles rather than planetesimals (Lambrechts and Johansen, 2012, 2014; Levison et al., 2015).”
Fossilized condensation lines in the Solar System protoplanetary disk (2015, background): “In fact, we have seen above that icy particles are expected to have had sizes of a few cm at 1 My at 2 AU (Lambrechts and Johansen, 2014).”