Separating gas-giant and ice-giant planets by halting pebble accretion
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In this paper, it was shown that the outer regions of planetary systems, where the mass required to halt pebble accretion is large, are dominated by ice giants and that gas-giant exoplanets in wide orbits are enriched by more than 50 Earth masses of solids.Abstract:
In the solar system giant planets come in two flavours: gas giants (Jupiter and Saturn) with massive gas envelopes, and ice giants (Uranus and Neptune) with much thinner envelopes around their cores. It is poorly understood how these two classes of planets formed. High solid accretion rates, necessary to form the cores of giant planets within the life-time of protoplanetary discs, heat the envelope and prevent rapid gas contraction onto the core, unless accretion is halted. We find that, in fact, accretion of pebbles (similar to cm sized particles) is self-limiting: when a core becomes massive enough it carves a gap in the pebble disc. This halt in pebble accretion subsequently triggers the rapid collapse of the super-critical gas envelope. Unlike gas giants, ice giants do not reach this threshold mass and can only bind low-mass envelopes that are highly enriched by water vapour from sublimated icy pebbles. This offers an explanation for the compositional difference between gas giants and ice giants in the solar system. Furthermore, unlike planetesimal-driven accretion scenarios, our model allows core formation and envelope attraction within disc life-times, provided that solids in protoplanetary discs are predominantly made up of pebbles. Our results imply that the outer regions of planetary systems, where the mass required to halt pebble accretion is large, are dominated by ice giants and that gas-giant exoplanets in wide orbits are enriched by more than 50 Earth masses of solids.read more
Citations
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Journal ArticleDOI
Age of Jupiter inferred from the distinct genetics and formation times of meteorites.
TL;DR: Jupiter is the oldest planet of the Solar System, and its solid core formed well before the solar nebula gas dissipated, consistent with the core accretion model for giant planet formation.
Journal ArticleDOI
Forming the cores of giant planets from the radial pebble flux in protoplanetary discs
TL;DR: In this paper, a simplified analytical model of dust coagulation and pebble drift in the outer disc, between 5 AU and 100 AU, was constructed, which gives the temporal evolution of the solid surface density and the dominant particle size.
Journal ArticleDOI
The growth of planets by pebble accretion in evolving protoplanetary discs
Abstract: The formation of planets depends on the underlying protoplanetary disc structure, which in turn influences both the accretion and migration rates of embedded planets. The disc itself evolves on time scales of several Myr, during which both temperature and density profiles change as matter accretes onto the central star. Here we used a detailed model of an evolving disc to determine the growth of planets by pebble accretion and their migration through the disc. Cores that reach their pebble isolation mass accrete gas to finally form giant planets with extensive gas envelopes, while planets that do not reach pebble isolation mass are stranded as ice giants and ice planets containing only minor amounts of gas in their envelopes. Unlike earlier population synthesis models, our model works without any artificial reductions in migration speed and for protoplanetary discs with gas and dust column densities similar to those inferred from observations. We find that in our nominal disc model, the emergence of planetary embryos preferably should occur after approximately 2 Myr in order to not exclusively form gas giants, but also ice giants and smaller planets. The high pebble accretion rates ensure that critical core masses for gas accretion can be reached at all orbital distances. Gas giant planets nevertheless experience significant reduction in semi-major axes by migration. Considering instead planetesimal accretion for planetary growth, we show that formation time scales are too long to compete with the migration time scales and the dissipation time of the protoplanetary disc. All in all, we find that pebble accretion overcomes many of the challenges in the formation of ice and gas giants in evolving protoplanetary discs.
Journal ArticleDOI
Forming Planets via Pebble Accretion
TL;DR: In this article, a review of all aspects of planet formation by pebble accretion, from dust growth over planetesimal formation to the accretion of protoplanets and fully grown planets with gaseous envelopes, is presented.
Journal ArticleDOI
The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au
Eric L. Nielsen,Robert J. De Rosa,Bruce Macintosh,Jason J. Wang,Jason J. Wang,Jean-Baptiste Ruffio,Eugene Chiang,Mark S. Marley,Didier Saumon,Dmitry Savransky,S. Mark Ammons,Vanessa P. Bailey,Travis Barman,Celia Blain,Joanna Bulger,Adam Burrows,Jeffrey Chilcote,Jeffrey Chilcote,Tara Cotten,Ian Czekala,Ian Czekala,René Doyon,Gaspard Duchêne,Gaspard Duchêne,Thomas M. Esposito,Daniel C. Fabrycky,Michael P. Fitzgerald,Katherine B. Follette,Jonathan J. Fortney,Benjamin L. Gerard,Benjamin L. Gerard,Stephen J. Goodsell,James R. Graham,Alexandra Z. Greenbaum,Pascale Hibon,Sasha Hinkley,Lea A. Hirsch,Justin Hom,Li Wei Hung,Rebekah I. Dawson,Patrick Ingraham,Paul Kalas,Paul Kalas,Quinn Konopacky,James E. Larkin,Eve J. Lee,Jonathan W. Lin,Jérôme Maire,Franck Marchis,Christian Marois,Christian Marois,Stanimir Metchev,Stanimir Metchev,Maxwell A. Millar-Blanchaer,Katie M. Morzinski,Rebecca Oppenheimer,David Palmer,Jennifer Patience,Marshall D. Perrin,Lisa Poyneer,Laurent Pueyo,Roman R. Rafikov,Abhijith Rajan,Julien Rameau,Fredrik T. Rantakyrö,Bin Ren,Adam C. Schneider,Anand Sivaramakrishnan,Inseok Song,Rémi Soummer,Melisa Tallis,Sandrine Thomas,Kimberly Ward-Duong,Schuyler Wolff +73 more
TL;DR: Nielsen et al. as discussed by the authors presented a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey (GPEES) to infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass.
References
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