Formation of short-period planets by disc migration

Daniel Carrera, Eric B. Ford, Andre Izidoro

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Protoplanetary discs are thought to be truncated at orbital periods of around 10 d. Therefore, the origin of rocky short-period planets with P < 10 d is a puzzle. We propose that many of these planets may form through the Type-I migration of planets locked into a chain of mutual mean motion resonances. We ran N-body simulations of planetary embryos embedded in a protoplanetary disc. The embryos experienced gravitational scatterings, collisions, disc torques, and dampening of orbital eccentricity and inclination. We then modelled Kepler observations of these planets using a forward model of both the transit probability and the detection efficiency of the Kepler pipeline. We found that planets become locked into long chains of mean motion resonances that migrate in unison. When the chain reaches the edge of the disc, the inner planets are pushed past the edge due to the disc torques acting on the planets farther out in the chain. Our simulated systems successfully reproduce the observed period distribution of short-period Kepler planets between 1 and 2 R. However, we obtain fewer closely packed short-period planets than in the Kepler sample. Our results provide valuable insight into the planet formation process, and suggests that resonance locks, migration, and dynamical instabilities play important roles in the formation and evolution of close-in small exoplanets.

Original languageEnglish (US)
Pages (from-to)3874-3885
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Jul 1 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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