Migration-driven diversity of super-Earth compositions. (6th June 2018)

• Record Type: Journal Article
• Authors: Raymond, Sean N; Boulet, Thibault; Izidoro, Andre; Esteves, Leandro; Bitsch, Bertram
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 479:Number 1(2018:Sep.)
• Page Start: L81
• Page End: L85
• Publication Date: 2018-06-06
• Subjects: protoplanetary discs -- planets and satellites: formation -- planets and satellites: dynamical evolution and stability -- planet-disc interactions -- planets and satellites: composition; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/sly100
• Languages: English
• ISSNs: 1745-3933

Abstract

ABSTRACT: A leading model for the origin of super-Earths proposes that planetary embryos migrate inward and pile up on close-in orbits. As large embryos are thought to preferentially form beyond the snowline, this naively predicts that most super-Earths should be very water-rich. Here we show that the shortest period planets formed in the migration model are often purely rocky. The inward migration of icy embryos through the terrestrial zone accelerates the growth of rocky planets via resonant shepherding. We illustrate this process with a simulation that provided a match to the Kepler-36 system of two planets on close orbits with very different densities. In the simulation, two super-Earths formed in a Kepler-36-like configuration; the inner planet was pure rock while the outer one was ice-rich. We conclude from a suite of simulations that the feeding zones of close-in super-Earths are likely to be broad and disconnected from their final orbital radii.