Hypothetical hyperbolic encounters between Venus and proto-Mercury that partially \ stripped away proto-Mercury's mantle

Abstract

Mercury has an unusually large metal core comprising ~70% of its mass comparing to all other terrestrial planets in the solar system. Giant impacts can remove a significant fraction of the silicate mantle of a chondritic proto-Mercury and form the iron rich present-day Mercury. However, such high-temperature giant impacts seem at odds with the retainment of moderately volatile elements on present-day Mercury (Peplowski et al. 2011). We simulated a series of hyperbolic encounters between proto-Mercury and proto-Venus, which may occur in the chaotic early solar system. Tidal disruption of proto-Mercury always removes part of its silicate mantle while its iron core remains intact. We find, in favourable cases, four close encounters with fast spinning projectiles (resulting from previous encounters) can lead to present-day Mercury iron fraction. More encounters are needed when the spin and orbital angular momentum are not always aligned. These hyperbolic encounters have various outcomes, such as orbital decay, binary planets and change of spin rates. These results suggest the importance of proper treatment of close encounters in N-body simulations of planetary accretion.

References in corpus (11)

• GIZMO: A New Class of Accurate, Mesh-Free Hydrodynamic Simulation Methods
• Formation of the Terrestrial Planets from a Narrow Annulus
• On the Dynamical Stability of the Solar System
• Forming Mercury by Giant Impacts
• Convergence of the critical cooling rate for protoplanetary disk fragmentation achieved; the key role of numerical dissipation of angular momentum
• Numerical aspects of Giant Impact simulations
• Enhanced mixing in giant impact simulations with a new Lagrangian method
• Dynamical Constraints on Mercury's Collisional Origin
• Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact
• Terrestrial Planet Formation: Constraining the Formation of Mercury
• Fate of the runner in hit-and-run collisions

Cited by in corpus (3)

• Dynamical avenues for Mercury's origin II: in-situ formation in the inner terrestrial disk
• Extreme close encounters between proto-Mercury and proto-Venus in terrestrial planet formation
• The Moon-forming Impact as a Constraint for the Inner Solar System's Formation