Isotopically distinct terrestrial planets via local accretion

Abstract

Combining isotopic constraints from meteorite data with dynamical models of planet formation proves to be advantageous in identifying the best model for terrestrial planet formation. Prior studies have shown that the probability of reproducing the distinct isotopic compositions of the Earth and Mars for both classical and Grand Tack models is very low. In the framework of the Grand Tack model, for Mars to be isotopically different from the Earth, it had to form under very specific conditions. Here, we subjected a fairly new and unexplored model--the depleted disc model--to the test. It presupposes that the region in the inner protoplanetary disc from Mars' orbit and beyond is depleted in mass such that Mars is left with insufficient material to grow to a larger size. Our aim is to test the whether the distinct isotopic compositions of the Earth and Mars are a natural outcome of this model. We found that the terrestrial planets accrete material mostly locally and have feeding zones that are sufficiently distinct. The Earth and Mars, and by extension, Venus, can have distinct isotopic compositions if there is an isotopic gradient in the terrestrial planet region of the protoplanetary disc. Our results suggest that the material in the inner Solar System most likely did not undergo substantial mixing that homogenised the potential isotopic gradient, in contrast to the Grand Tack model where the feeding zones of the terrestrial planets are nearly identical due to the mixing of material by Jupiter's migration.

18 pages, 11 figures, 2 tables, accepted for publication in Icarus

References in corpus (17)

• A low mass for Mars from Jupiter's early gas-driven migration
• A torque formula for non-isothermal Type I planetary migration - II. Effects of diffusion
• Equilibration in the Aftermath of the Lunar-Forming Giant Impact
• Formation of the Terrestrial Planets from a Narrow Annulus
• On the formation of planetary systems via oligarchic growth in thermally evolving viscous discs
• Mars' Growth Stunted by an Early Giant Planet Instability
• The radial dependence of pebble accretion rates: A source of diversity in planetary systems I. Analytical formulation
• Chaotic diffusion in the Solar System
• 60Fe-60Ni chronology of core formation in Mars
• Terrestrial Planet Formation Constrained by Mars and the Structure of the Asteroid Belt
• The Feeding Zones of Terrestrial Planets and Insights into Moon Formation
• Terrestrial Planet Formation in a protoplanetary disk with a local mass depletion: A successful scenario for the formation of Mars
• Planetesimals to Terrestrial Planets: collisional evolution amidst a dissipating gas disk
• Analysis of terrestrial planet formation by the Grand Tack model: System architecture and tack location
• The cool and distant formation of Mars
• Jupiter's influence on the building blocks of Mars and Earth
• The curious case of Mars formation

Cited by in corpus (12)

• Growing Mars fast: High-resolution GPU simulations of embryo formation
• Terrestrial planet formation from a ring
• The terrestrial planet formation paradox inferred from high-resolution N-body simulations
• Effects of pebble accretion on the growth and composition of planetesimals in the inner Solar System
• Mercury's formation within the Early Instability Scenario
• Mars' formation can constrain the primordial orbits of the gas giants
• Accretion regions of meteorite parent bodies inferred from a two-endmember isotopic mixing model
• Terrestrial planet formation during giant planet formation and giant planet migration I: The first 5 million years
• Constraining the Origin of Mars via Simulations of Multi-Stage Core Formation
• Evidence of a primordial isotopic gradient in the inner region of the solar protoplanetary disc
• Spatial distribution of isotopes and compositional mixing in the inner protoplanetary disk
• Impact chronology of leftover planetesimals