A pebble accretion model for the formation of the terrestrial planets in the Solar System

Abstract

Pebbles of millimeter sizes are abundant in protoplanetary discs around young stars. Chondrules inside primitive meteorites - formed by melting of dust aggregate pebbles or in impacts between planetesimals - have similar sizes. The role of pebble accretion for terrestrial planet formation is nevertheless unclear. Here we present a model where inwards-drifting pebbles feed the growth of terrestrial planets. The masses and orbits of Venus, Earth, Theia (which later collided with the Earth to form the Moon) and Mars are all consistent with pebble accretion onto protoplanets that formed around Mars' orbit and migrated to their final positions while growing. The isotopic compositions of Earth and Mars are matched qualitatively by accretion of two generations of pebbles, carrying distinct isotopic signatures. Finally, we show that the water and carbon budget of Earth can be delivered by pebbles from the early generation before the gas envelope became hot enough to vaporise volatiles.

Science Advances, in press

References in corpus (7)

• The origins and concentrations of water, carbon, nitrogen and noble gases on Earth
• The Radial Distribution of Dust Particles in the HL Tau Disk from ALMA and VLA Observations
• A water budget dichotomy of rocky protoplanets from ${}^{26}$Al-heating
• Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line
• Formation of Early Water Oceans on Rocky Planets
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• Dynamical Evolution of the Earth-Moon Progenitors - Whence Theia?

Cited by in corpus (2)

• Collision Chains among the Terrestrial Planets. III. Formation of the Moon
• Collision Chains among the Terrestrial Planets. II. An Asymmetry between Earth and Venus