Query : 2021A&A...650A.152I

2021A&A...650A.152I - Astronomy and Astrophysics, volume 650A, 152-152 (2021/6-1)

Formation of planetary systems by pebble accretion and migration. Hot super-Earth systems from breaking compact resonant chains.


Abstract (from CDS):

At least 30% of main sequence stars host planets with sizes of between 1 and 4 Earth radii and orbital periods of less than 100 days. We use N-body simulations including a model for gas-assisted pebble accretion and disk-planet tidal interaction to study the formation of super-Earth systems. We show that the integrated pebble mass reservoir creates a bifurcation between hot super-Earths or hot-Neptunes (≤15M) and super-massive planetary cores potentially able to become gas giant planets (≥15M). Simulations with moderate pebble fluxes grow multiple super-Earth-mass planets that migrate inwards and pile up at the inner edge of the disk forming long resonant chains. We follow the long-term dynamical evolution of these systems and use the period ratio distribution of observed planet-pairs to constrain our model. Up to ∼95% of resonant chains become dynamically unstable after the gas disk dispersal, leading to a phase of late collisions that breaks the original resonant configurations. Our simulations naturally match observations when they produce a dominant fraction (≥95%) of unstable systems with a sprinkling (≤5%) of stable resonant chains (the Trappist-1 system represents one such example). Our results demonstrate that super-Earth systems are inherently multiple (N≥2) and that the observed excess of single-planet transits is a consequence of the mutual inclinations excited by the planet-planet instability. In simulations in which planetary seeds are initially distributed in the inner and outer disk, close-in super-Earths are systematically ice rich. This contrasts with the interpretation that most super-Earths are rocky based on bulk-density measurements of super-Earths and photo-evaporation modeling of their bimodal radius distribution. We investigate the conditions needed to form rocky super-Earths. The formation of rocky super-Earths requires special circumstances, such as far more efficient planetesimal formation well inside the snow line, or much faster planetary growth by pebble accretion in the inner disk. Intriguingly, the necessary conditions to match the bulk of hot super-Earths are at odds with the conditions needed to match the Solar System.

Abstract Copyright: © ESO 2021

Journal keyword(s): planets and satellites: formation - planets and satellites: dynamical evolution and stability - planets and satellites: detection - planets and satellites: composition - methods: numerical - planet-disk interactions

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 V* HL Tau Or* 04 31 38.5107609312 +18 13 57.859747968   15.89 14.49 14.39   K5 1401 0
2 Kepler-36 Er* 19 25 00.0428079600 +49 13 54.630900876   12.795 12.174 12.094   F2 213 1
3 Kepler-100 Er* 19 25 32.6432787456 +41 59 24.945100548   12.009 11.278 11.128   G3 107 0
4 Kepler-142 Er* 19 40 28.5407018232 +48 28 52.654331856   14.101 13.318 13.177   ~ 59 0
5 Kepler-11 Er* 19 48 27.6226218768 +41 54 32.903163504   14.635 13.838 13.742   G2V 341 1
6 Kepler-223 Er* 19 53 16.4202435936 +47 16 46.308434088   16.209 15.570 15.78   ~ 150 1
7 TRAPPIST-1 LM* 23 06 29.3684948589 -05 02 29.037301866     18.798 16.466 14.024 M7.5e 928 0

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