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Astrophysical measurements have shown that some stars have sufficiently high carbon-to-oxygen ratios such that the planets they host would be mainly composed of carbides instead of silicates. We studied the behavior of silicon carbide in…
Rocky planet atmospheres form and evolve through interactions between the planet's surface and interior. If a growing rocky planet acquires enough mass prior to the dissipation of the nebular gas disk, it can gravitationally capture a…
Close-in transiting sub-Neptunes are abundant in our galaxy \cite{fulton2017california}. Planetary interior models based on their observed radius-mass relationship suggest that sub-Neptunes contain a discernible amount of either hydrogen…
Many planets in the solar system and across the galaxy have hydrogen-rich atmospheres overlying more heavy element-rich interiors with which they interact for billions of years. Atmosphere-interior interactions are thus crucial to…
Hydrocarbon mixtures are extremely abundant in the Universe, and diamond formation from them can play a crucial role in shaping the interior structure and evolution of planets. With first-principles accuracy, we first estimate the diamond…
A recent paper of Dias and Silvera (DS) reports on production of metallic hydrogen in a diamond anvil cell at 495 GPa at 5.5 and 83 K. The results are implied to have a great impact on energy and rocketry. Here we argue that the presented…
Sub-Neptune exoplanets are commonly hypothesized to consist of a silicate-rich magma ocean topped by a hydrogen-rich atmosphere. Previous work studying the outgassing of silicate material has demonstrated that such atmosphere-interior…
From an astrobiological point of view, special attention has been paid to the probability of habitable planets in extrasolar systems. The purpose of this study is to constrain a possible range of the mass of a terrestrial planet that can…
We study water-hydrogen mixtures under planetary interior conditions using ab initio molecular dynamics simulations. We determine the thermodynamic properties of various water-hydrogen mixing ratios at temperatures of 2000 and 6000 K for…
Many sub-Neptune exoplanets have been believed to be composed of a thick hydrogen-dominated atmosphere and a high-temperature heavier-element-dominant core. From an assumption that there is no chemical reaction between hydrogen and…
Silica, water and hydrogen are known to be the major components of celestial bodies, and have significant influence on the formation and evolution of giant planets, such as Uranus and Neptune. Thus, it is of fundamental importance to…
Warm dense matter is present at the heart of gas giants and large exo-planets. Yet, its most basic properties are unknown and limit our understanding of planetary formation and evolution. In this state, where pressure climbs above 1 Mbar,…
Existence of strongly bound water molecules on silicate surfaces, above the desorption temperature of water ice, has been first predicted by computational studies and recently demonstrated by laboratory experiments. Such trapped water may…
Water is abundant in natural environments but the form it resides in planetary interiors remains uncertain. We report combined synchrotron X-ray diffraction and optical spectroscopy measurements of H2O in the laser-heated diamond anvil cell…
We present results from ab initio simulations of liquid water-hydrogen mixtures in the range from 2 to 70 GPa and from 1000 to 6000 K, covering conditions in the interiors of ice giant planets and parts of the outer envelope of gas giant…
The chemical behavior of water under extreme pressures and temperatures lies at the heart of processes shaping planetary interiors, influences the deep carbon cycle, and underpins innovative high-temperature, high-pressure synthesis of…
Hot rocky super-Earths are thought to be sufficiently irradiated by their host star to melt their surface and thus allow for long-lasting magma oceans. Some processes have been proposed for such planets to have retained primordial hydrogen…
Hydrogen and helium are the most abundant elements in the universe and they constitute the interiors of gas giant planets. Thus, their equations of states, phase, chemical state, and chemical reactivity at extreme conditions are of great…
In the quest to make metallic hydrogen at low temperatures a rich number of new phases have been found and the highest pressure ones have somewhat flat phase lines, around room temperature. We have studied hydrogen to static pressures of…
Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes…