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Earth’s core-mantle segregation set the initial conditions for its subsequent evolution. However, the effect of water on core-mantle element partitioning remains poorly constrained. Using machine learning molecular dynamics simulations trained on quantum mechanical data, we show that increasing water content promotes magnesium partitioning into the metallic core, whereas silicon, iron, and hydrogen increasingly prefer the silicate mantle. On the basis of Earth’s core mass fraction and oxygen fugacity during core formation, a self-consistent hydrous core-mantle differentiation model yields a bulk Earth water content of ~0.23 weight % (equivalently ~10 ocean masses), a bulk Earth magnesium/silicon ratio of 1.16 ± 0.01, and a mantle magnesium/silicon ratio of 1.25 to 1.28. The initial core would contain 3.5 to 4.1 weight % silicon, 2.9 to 3.1 weight % oxygen, 0.11 to 0.14 weight % magnesium, and 0.04 to 0.10 weight % hydrogen, along with sulfur and carbon. We predict that super-Earths can retain large metallic cores even with several weight % water. 

Abstract Thermophysical properties of silicate liquids under extreme conditions are critical for understanding the accretion and evolution of super‐Earths and sub‐Neptunes. The thermal equation of state and viscosity of silicate liquids determine the adiabatic profiles and dynamics of magma oceans. However, these properties are challenging to constrain at elevated pressures in experiments. Here, we perform ab initio molecular dynamics simulations of MgSiO₃liquid across a wide range of pressures (0–1,200 GPa) and temperatures (2200–14000 K) and analyze its structure, the Grüneisen parameter, and viscosity. Our results reveal the clear temperature and pressure dependence of the Grüneisen parameter, which varies synchronously with the O‐O coordination number. The Grüneisen parameter shifts from positive to negative temperature dependence between ∼20 and 70 GPa, corresponding to a peak in the O‐O coordination number and SiO₅abundance. Initially, the Grüneisen parameter increases with pressure and then decreases, showing limited temperature dependence above ∼300 GPa, where its behavior resembles that of solids. Furthermore, we determine the adiabat and viscosity profiles of magma oceans in super‐Earths and sub‐Neptunes. The results suggest that the mantles of super‐Earths and sub‐Neptunes may solidify either from the bottom up or at pressures of ∼120–150 GPa, depending on the curvature of the mantle melting line. The low viscosity of magma oceans likely enhances convective currents and facilitate efficient differentiation. These thermophysical properties, now quantified up to terapascal pressures, enable updates to the mass‐radius relation of magma ocean exoplanets, showing notable differences compared to their solid counterparts. 

Abstract The precipitation of magnesium oxide (MgO) from the Earth's core has been proposed as a potential energy source to power the geodynamo prior to the inner core solidification. Yet, the stable phase and exact amount of MgO exsolution remain elusive. Here we utilize an iterative learning scheme to develop a unified deep learning interatomic potential for the Mg‐Fe‐O system valid over a wide pressure‐temperature range. This potential enables direct, large‐scale simulations of MgO exsolution processes at the Earth's core‐mantle boundary. Our results suggest that Mg exsolve in the form of crystalline Fe‐poor ferropericlase as opposed to a liquid MgO component presumed previously. The solubility of Mg in the core is limited, and the present‐day core is nearly Mg‐free. The resulting exsolution rate is small yet nonnegligible, suggesting that MgO exsolution may provide a potentially important energy source, although it alone may be difficult to drive an early geodynamo. 

Radiogenic heat production is fundamental to the energy budget of planets. Roughly half of the heat that Earth loses through its surface today comes from the three long-lived, heat-producing elements (potassium, thorium, and uranium). These three elements have long been believed to be highly lithophile and thus concentrate in the mantle of rocky planets. However, our study shows that they all become siderophile under the pressure and temperature conditions relevant to the core formation of large rocky planets dubbed super-Earths. Mantle convection in super-Earths is then primarily driven by heating from the core rather than by a mix of internal heating and cooling from above as in Earth. Partitioning these sources of radiogenic heat into the core remarkably increases the core-mantle boundary (CMB) temperature and the total heat flow across the CMB in super-Earths. Consequently, super-Earths are likely to host long-lived volcanism and strong magnetic dynamos. 

Abstract Earth's accretion was highly energetic and likely involved multiple global melting events. Following the Moon‐forming giant impact, extensive mantle melting and the separation of solids and melts under deep mantle pressures likely produced a basal magma ocean (BMO) beneath the solidified mantle. The presence and evolution of the BMO have been proposed to explain key geophysical and geochemical features of the lowermost mantle. Understanding the evolution of the BMO is crucial for testing these hypotheses, but its interaction with the core presents a significant challenge, as the mechanism of this exchange remains unclear. In this study, we develop a theoretical framework to assess the regime of BMO‐core exchange based on the compositions of the BMO and the core. We propose that during solidification, the BMO may evolve into a regime where the reaction at the BMO‐core interface drives compositional convection in liquids on both sides, if the core has a high enough Si content (–, under the assumption that the O content is –). In this scenario, the BMO‐core exchange would be much more efficient than previously estimated, buffering the tendency of FeO enrichment during crystallization and shortening the lifetime of the BMO. 

Abstract Metabolic scaling theory has been pivotal in formalizing the expected energy expenditures across populations as a function of body size. Coexistence theory has provided a mathematization of the environmental conditions compatible with multispecies coexistence. Yet, it has been challenging to explain how observed community‐wide patterns, such as the inverse relationship between population abundance density and body size, can be unified under both theories. Here, we provide the foundation for a tractable, scalable, and extendable framework to study the coexistence of resource‐mediated competing populations as a function of their body size. For a given thermal domain and response, this integration reveals that the metabolically predicted 1/4 power dependence of carrying capacity of biomass density on body size can be understood as the average distribution of carrying capacities across feasible environmental conditions, especially for large communities. In line with empirical observations, our integration predicts that such average distribution leads to communities in which population biomass densities at equilibrium are independent from body size, and consequently, population abundance densities are inversely related to body size. This integration opens new opportunities to increase our understanding of how metabolic scaling relationships at the population level can shape processes at the community level under changing environments.