Evidence of a primordial isotopic gradient in the inner region of the solar protoplanetary disc

Abstract

Not only do the sampled terrestrial worlds (Earth, Mars, and asteroid 4 Vesta) differ in their mass-independent (nucleosynthetic) isotopic compositions of many elements (e.g. ${\epsilon }^{48}$Ca, ${\epsilon }^{50}$Ti, ${\epsilon }^{54}$Cr, ${\epsilon }^{92}$Mo), the magnitudes of some of these isotopic anomalies also appear to correlate with heliocentric distance. While the isotopic differences between the Earth and Mars may be readily accounted for by the accretion of mostly local materials in distinct regions of the protoplanetary disc, it is unclear whether this also applies to asteroid Vesta. Here we analysed the available data from our numerical simulation database to determine the formation location of Vesta in the framework of three planet-formation models: classical, Grand Tack, and Depleted Disc. We find that Vesta has a high probability of forming locally in the asteroid belt in models where material mixing in the inner disc is limited; this limited mixing is implied by the isotopic differences between the Earth and Mars. Based on our results, we propose several criteria to explain the apparent correlation between the different nucleosynthetic isotopic compositions of the Earth, Mars, and Vesta: (1) these planetary bodies accreted their building blocks in different regions of the disc, (2) the inner disc is characterised by an isotopic gradient, and (3) the isotopic gradient was preserved during the formation of these planetary bodies and was not diluted by material mixing in the disc (e.g. via giant planet migration).

References in corpus (17)

• Dynamics of the giant planets of the solar system in the gaseous proto-planetary disk and relationship to the current orbital architecture
• The structure of protoplanetary discs around evolving young stars
• Short-lived Nuclei in the Early Solar System: Possible AGB Sources
• Compositional distributions and evolutionary processes for the near-Earth object population: Results from the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS
• Bifurcation of planetary building blocks during Solar System formation
• Highly siderophile elements were stripped from Earth's mantle by iron sulfide segregation
• Terrestrial planet formation from lost inner solar system material
• The GENGA Code: Gravitational Encounters in N-body simulations with GPU Acceleration
• The Feeding Zones of Terrestrial Planets and Insights into Moon Formation
• The origin of s-process isotope heterogeneity in the solar protoplanetary disk
• Isotopic evolution of the inner Solar System inferred from molybdenum isotopes in meteorites
• Triggered Star Formation Inside the Shell of a Wolf-Rayet Bubble as the origin of the Solar System
• The Asteroid Belt as a Relic From a Chaotic Early Solar System
• Growing Mars fast: High-resolution GPU simulations of embryo formation
• Hungaria Asteroid Family as the Source of Aubrite Meteorites
• Constraints on terrestrial planet formation timescales and equilibration processes in the Grand Tack scenario from Hf-W isotopic evolution
• Isotopically distinct terrestrial planets via local accretion

Cited by in corpus (2)

• Predicting the Dominant Formation Mechanism of Multi-Planetary Systems
• Spatial distribution of isotopes and compositional mixing in the inner protoplanetary disk