The "Breaking The Chains" migration model for super-Earths formation: the effect of collisional fragmentation

Abstract

Planets between 1-4 Earth radii with orbital periods <100 days are strikingly common. The migration model proposes that super-Earths migrate inwards and pile up at the disk inner edge in chains of mean motion resonances. After gas disk dispersal, simulations show that super-Earth's gravitational interactions can naturally break their resonant configuration leading to a late phase of giant impacts. The instability phase is key to matching the orbital spacing of observed systems. Yet, most previous simulations have modelled collisions as perfect accretion events, ignoring fragmentation. In this work, we investigate the impact of imperfect accretion on the breaking the chains scenario. We performed N-body simulations starting from distributions of planetary embryos and modelling the effects of pebble accretion and migration in the gas disk. Our simulations also follow the long-term dynamical evolution of super-Earths after the gas disk dissipation. We compared the results of simulations where collisions are treated as perfect merging events with those where imperfect accretion and fragmentation are allowed. We concluded that the perfect accretion is a suitable approximation in this regime, from a dynamical point of view. Although fragmentation events are common, only ~10% of the system mass is fragmented during a typical "late instability phase", with fragments being mostly reacreted by surviving planets. This limited total mass in fragments proved to be insufficient to alter qualitatively the final system dynamical configuration -- e.g. promote strong dynamical friction or residual migration -- compared to simulations where fragmentation is neglected.

13 pages, 8 figures and 1 table. Accepted for publication in MNRAS

References in corpus (25)

• Migration and the formation of systems of hot super-Earths and Neptunes
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• Three-dimensional simulations of multiple protoplanets embedded in a protostellar disc
• On the formation of planetary systems via oligarchic growth in thermally evolving viscous discs
• Formation of planetary systems by pebble accretion and migration: Growth of gas giants
• Observable Consequences of Planet Formation Models in Systems with Close-in Terrestrial Planets
• Hot super-Earths and giant planet cores from different migration histories
• Collisional Stripping and Disruption of Super-Earths
• A reassessment of the in situ formation of close-in super-Earths
• Planetesimal Interactions Can Explain the Mysterious Period Ratios of Small Near-Resonant Planets
• The early instability scenario: terrestrial planet formation during the giant planet instability, and the effect of collisional fragmentation
• Occurrence and core-envelope structure of 1--4x Earth-size planets around Sun-like stars
• A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e
• Planet formation and migration near the silicate sublimation front in protoplanetary disks
• Magnetospheric Gap and Accumulation of Giant Planets Close to the Star
• Terrestrial Planet Formation from an Annulus
• Chemical Diversity of Super-Earths As a Consequence of Formation
• Rocklines as Cradles for Refractory Solids in the Protosolar Nebula
• Formation of compact systems of super-Earths via dynamical instabilities and giant impacts
• The effect of a strong pressure bump in the Sun's natal disk: Terrestrial planet formation via planetesimal accretion rather than pebble accretion
• Formation of short-period planets by disk migration
• The circulation of dust in protoplanetary discs and the initial conditions of planet formation
• The origins of nearly coplanar, non-resonant systems of close-in super-Earths
• Studying the Evolution of Warm Dust Encircling BD +20 307 Using SOFIA

Cited by in corpus (15)

• The Exoplanet Radius Valley from Gas-driven Planet Migration and Breaking of Resonant Chains
• Architectures of Compact Super-Earth Systems Shaped by Instabilities
• Giants are bullies: how their growth influences systems of inner sub-Neptunes and super-Earths
• Forming super-Mercuries: The role of stellar abundances
• Intra-system uniformity: a natural outcome of dynamical sculpting
• Explaining Mercury via a single giant impact is highly unlikely
• Rocky histories: The effect of high excitations on the formation of rocky planets
• On the Degree of Dynamical Packing in the Kepler Multi-planet Systems
• Assessing the spin-orbit obliquity of low-mass planets in the breaking the chain formation model: A story of misalignment
• Can metal-rich worlds form by giant impacts?
• Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1
• Diversity of disc viscosities can explain the period ratios of resonant and non-resonant systems of hot super-Earths and mini-Neptunes
• Orbital structure of planetary systems formed by giant impacts: stellar mass dependence
• Protoplanet collisions: new scaling laws from SPH simulations
• How stellar mass and disc size shape the formation and migration of super-Earths