The shock physics of giant impacts: Key requirements for the equations of state

Stewart, S. T.; Davies, E. J.; Duncan, M. S.; Lock, S. J.; Root, Seth; Townsend, Joshua P; Kraus, R. G.; Caracas, Razvan; Jacobsen, S. B.

doi:10.1063/12.0000946

Cited by 34 publications

(62 citation statements)

References 24 publications

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“…Despite this assumption, an in-depth study of the critical behavior of SiO 2 by Connolly (2016) suggests that the width of the liquid-vapor phase boundary in SiO 2 is relatively narrow and thus is likely smaller than the uncertainties on the densities of the coexisting liquid and vapor from our calculations, as shown in Figure 4. In accordance with other silica-bearing systems studied thus far, the assumption of single component-like critical behavior seems reasonable given the current state of knowledge of these materials and the capabilities of current hydrodynamic simulation techniques (Connolly, 2016;Kraus et al, 2012;Xiao & Stixrude, 2018;Stewart et al, 2020).…”

Section: Resultssupporting

confidence: 73%

“…Canup, 2012; Cuk & Stewart, 2012; Lock & Stewart, 2017; Nakajima & Stevenson, 2014). In the ANEOS model for forsterite, for example, the critical point is at 1.68 g/cm 3 , 8800 K, and 10 kbar, while our results suggest a critical point at 0.52 g/cm 3 , 6230 K, and 1.22 kbar (Stewart et al, 2020). This is significant as is suggests that nearly all accretionary collisions produce some amount of vaporization (Davies et al, 2020).…”

Section: Resultscontrasting

confidence: 51%

“…With one point on the liquid-vapor phase boundary in hand, we estimated the limits of coexistence below the critical point via the familiar Maxwell equal-area construction (Callen, 2006). Famously, renormalization group theory applied to critical behavior in the 3D Ising model gives an analytic form for the phase boundaries for the vapor and liquid sides of the vapor dome: (Stewart et al, 2020).…”

Section: Critical Point Estimation and Uncertainty Quantificationmentioning

confidence: 99%

See 2 more Smart Citations

Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations

Townsend

Shohet

Cochrane

2020

Geophysical Research Letters

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Hypervelocity impact‐driven vaporization is characteristic of late‐stage planet formation. Yet the behavior and properties of liquid‐vapor mixtures of planetary materials of interest are typically unknown. Multiphase equations of state used in hydrodynamic simulations of planet impacts therefore lack reliable data for this important phenomenon. Here, we present the first constraints on the liquid‐vapor critical point and coexistence phase boundary of Mg2SiO4 computed from ab initio molecular dynamics simulations. We found that the vapor is depleted in magnesium and enriched in silica and oxygen, while the coexisting liquid is enriched in magnesium and depleted in oxygen, from which we infer vaporization is incongruent. The critical point was estimated from an equation of state fit to the data. The results are in line with recent calculations of MgSiO3 and together confirm that extant multiphase equation of state (EOS) models used in planetary accretion modeling significantly underestimate the amount of supercritical material postimpact.

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Section: Resultssupporting

confidence: 73%

Section: Resultscontrasting

confidence: 51%

Section: Critical Point Estimation and Uncertainty Quantificationmentioning

confidence: 99%

See 1 more Smart Citation

Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations

Townsend

Shohet

Cochrane

2020

Geophysical Research Letters

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“…Specific entropies at 50% vaporization are not experimentally constrained and vary greatly among the model calculations. For this work, we use the model vapor curve from Stewart et al (), labeled new ANEOS in Figure . While this work experimentally constrains the specific entropy of the principal forsterite Hugoniot, the pressure‐volume‐temperature states at higher pressures on the liquid‐vapor dome still need experimental validation.…”

Section: Shock‐induced Phase Changesmentioning

confidence: 99%

Silicate Melting and Vaporization During Rocky Planet Formation

et al. 2020

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Collisions that induce melting and vaporization can have a substantial effect on the thermal and geochemical evolution of planets. However, the thermodynamics of major minerals are not well known at the extreme conditions attained during planet formation. We obtained new data at the Sandia Z Machine and use published thermodynamic data for the major mineral forsterite (Mg 2SiO 4) to calculate the specific entropy in the liquid region of the principal Hugoniot. We use our calculated specific entropy of shocked forsterite, and revised entropies for shocked silica, to determine the critical impact velocities for melting or vaporization upon decompression from the shocked state to 1 bar and the triple points, which are near the pressures of the solar nebula. We also demonstrate the importance of the initial temperature on the criteria for vaporization. Applying these results to N‐body simulations of terrestrial planet formation, we find that up to 20% to 40% of the total system mass is processed through collisions with velocities that exceed the criteria for incipient vaporization at the triple point. Vaporizing collisions between small bodies are an important component of terrestrial planet formation.

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“…Recently, the shock states for forsterite were measured at pressures from 200 to 950 GPa, to determine the relationships between pressure (P), density (ρ), temperature (T), and specific entropy (S) (Davies et al, 2020;Root et al, 2018). Stewart et al (2020) found substantial differences between previous ANEOS models for forsterite and these new data, and developed improvements to the ANEOS code package to improve the fit to experimental temperatures and entropies.…”

mentioning

confidence: 99%

Temperature and Density on the Forsterite Liquid‐Vapor Phase Boundary

et al. 2021

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During terrestrial planet formation, impacts were a widespread and fundamental process (Chambers, 2010), the scale of which ranged from small impacts between planetesimals to giant impacts such as the Moon-forming impact. The post-impact structures of a giant impact depend upon the specific parameters of the impact. The equations of state (EOS) of the constituent materials are necessary to enable calculation of the energy deposited by the event and the internal structure, including the amount of melting and vaporization. Previous work has found that energetic, high-angular momentum impacts create synestias (Lock & Stewart, 2017;Lock et al., 2018) and less energetic impacts form a more traditional planet and disk structures (Canup et al., 2013). Understanding the evolution of planetary bodies after a giant impact requires robust EOS models.

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The shock physics of giant impacts: Key requirements for the equations of state

Cited by 34 publications

References 24 publications

Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations

Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations

Silicate Melting and Vaporization During Rocky Planet Formation

Temperature and Density on the Forsterite Liquid‐Vapor Phase Boundary

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The shock physics of giant impacts: Key requirements for the equations of state

Cited by 34 publications

References 24 publications

Liquid‐Vapor Coexistence and Critical Point of Mg2SiO4 From Ab Initio Simulations

Liquid‐Vapor Coexistence and Critical Point of Mg2SiO4 From Ab Initio Simulations

Silicate Melting and Vaporization During Rocky Planet Formation

Temperature and Density on the Forsterite Liquid‐Vapor Phase Boundary

Contact Info

Product

Resources

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Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations

Liquid‐Vapor Coexistence and Critical Point of Mg₂SiO₄ From Ab Initio Simulations