Breaking the chains: hot super-Earth systems from migration and disruption of compact resonant chains

By A. Izidoro, M. Ogihara, S. Raymond, A. Morbidelli, A. Pierens, B. Bitsch, C. Cossou, F. Hersant. 2017

252 citations recorded by the source corpus.

'Hot super-Earths' (or 'mini-Neptunes') between one and four times Earth's size with period shorter than 100 d orbit 30-50 per cent of Sun-like stars. Their orbital configuration - measured as the period ratio distribution of adjacent planets in multiplanet systems - is a strong constraint for formation models. Here, we use N-body simulations with synthetic forces from an underlying evolving gaseous disc to model the formation and long-term dynamical evolution of super-Earth systems. While the gas disc is present, planetary embryos grow and migrate inward to form a resonant chain anchored at the inner edge of the disc. These resonant chains are far more compact than the observed super-Earth systems. Once the gas dissipates, resonant chains may become dynamically unstable. They undergo a phase of giant impacts that spreads the systems out. Disc turbulence has no measurable effect on the outcome. Our simulations match observations if a small fraction of resonant chains remain stable, while most super- Earths undergo a late dynamical instability. Our statistical analysis restricts the contribution of stable systems to less than 25 per cent. Our results also suggest that the large fraction of observed single-planet systems does not necessarily imply any dichotomy in the architecture of planetary systems. Finally, we use the low abundance of resonances in Kepler data to argue that, in reality, the survival of resonant chains happens likely only in ~5 per cent of the cases. This leads to a mystery: in our simulations only 50-60 per cent of resonant chains became unstable, whereas at least 75 per cent (and probably 90-95 per cent) must be unstable to match observations.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/945dc01a6f72a8e00692c4287b39db67d9aacbb6

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. D. Fabrycky
2. G. Mulders
3. Ilaria Pascucci
4. C. Petrovich
5. M. Gillon
6. D. Queloz
7. F. Selsis
8. D. Charbonneau

In Geophysics

1. J. Leconte
2. S. Raymond
3. K. Heng
4. C. Dorn
5. C. Petrovich

Citations in the corpus

• The Exoplanet Population Observation Simulator. I. The Inner Edges of Planetary Systems (2018, background): “These mechanisms include dynamical instabilities within systems (Pu & Wu 2015; Volk & Gladman 2015), external perturbations from giant planets or stars (Johansen et al. 2012; Hansen 2017; Izidoro et al. 2017; Lai & Pu 2017; Cai et al. 2018) and host star misalignment (Spalding & Batygin 2016).”
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of Their Intrinsic Architecture (2018, background): “It is also unclear, in such a framework, how to account for the diverse multiple systems and their current dynamical states (but see Izidoro et al. 2017).”
• The nature of the TRAPPIST-1 exoplanets. (2018, background): “The fact that all seven plan- ets form a single resonant chain indicates that the entire system migrated in concert (Cossou et al. 2014; Izidoro et al. 2017).”