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It was recently discovered that the temperature in the surface layer of externally heated optically thick gray dust clouds increases with the optical depth for some distance from the surface, as opposed to the normal decrease in temperature…

Astrophysics · Physics 2008-11-26 Dejan Vinkovic

The dynamics of the discrete Gaussian model for the surface of a crystal deposited on a disordered substrate is investigated by Monte Carlo simulations. The mobility of the growing surface was studied as a function of a small driving force…

Condensed Matter · Physics 2009-10-28 D. Cule

We report the first successful simulation of spontaneous formation of surface magnetic structures from a large-scale dynamo by strongly-stratified thermal convection in Cartesian geometry. The large-scale dynamo observed in our…

Solar and Stellar Astrophysics · Physics 2016-05-25 Youhei Masada , Takayoshi Sano

Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. Especially, saturated, hydrogen-rich molecules are formed through surface chemistry.…

Astrophysics of Galaxies · Physics 2022-02-11 H. M. Cuppen , A. Fredon , T. Lamberts , E. M. Penteado , M. Simons , C. Walsh

Twisted magnetic fields are frequently seen to emerge above the visible surface of the Sun. This emergence is usually associated with the rise of buoyant magnetic flux structures. Here we ask how magnetic fields from a turbulent large-scale…

Solar and Stellar Astrophysics · Physics 2010-11-22 J. Warnecke , A. Brandenburg

Irradiation of a sharp tungsten tip by a femtosecond laser and exposed to a strong DC electric field led to gradual and reproducible surface modifications. By a combination of field emission microscopy and scanning electron microscopy, we…

There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…

Earth and Planetary Astrophysics · Physics 2015-10-21 David W. Marshall , H. R. Sadeghpour

With seven temperate Earth-sized planets revolving around an ultracool red dwarf, the nearby TRAPPIST-1 system offers a unique opportunity to verify models of exoplanet composition, differentiation, and interior structure. In particular,…

Earth and Planetary Astrophysics · Physics 2026-01-06 Dongyang Huang , Caroline Dorn

Using density-functional theory we assess the stability of bulk and surface oxides of the late 4d transition metals in a ``constrained equilibrium'' with a gas phase formed of O2 and CO. While the stability range of the most stable bulk…

Materials Science · Physics 2009-11-10 Karsten Reuter , Matthias Scheffler

Recently discovered exoplanets on close-in orbits should have surface temperatures of 100's to 1000's of K. They are likely tidally locked and synchronously rotating around their parent stars and, if an atmosphere is absent, have surface…

Earth and Planetary Astrophysics · Physics 2015-05-28 Joost van Summeren , Clinton P. Conrad , Eric Gaidos

We have investigated the formation of tungsten oxide nanowires under different CVD conditions. We find that exposure of oxidized tungsten films to hydrogen and methane at 900C leads to the formation of a dense array of typically 10 nm…

Materials Science · Physics 2015-07-20 Christian Klinke , James B. Hannon , Lynne Gignac , Kathleen Reuter , Phaedon Avouris

We use Monte Carlo simulations to study the finite temperature behavior of vortices in the XY- model for tangent vector order on curved backgrounds. Contrary to naive expectations, we show that the underlying geometry does not affect the…

Statistical Mechanics · Physics 2018-01-24 Leopoldo R. Gómez , Nicolás A. García , Daniel A. Vega , José Lorenzana

We investigate the impact of nightside cloud formation on the observable night-day contrast of tidally-locked terrestrial planet atmospheres. We demonstrate that, in the case where the planetary dayside is only 10s of Kelvin hotter than the…

Earth and Planetary Astrophysics · Physics 2024-09-13 Diana Powell , Robin Wordsworth , Karin Öberg

The equilibrium crystal shape (ECS) of oxygen-covered tungsten micricrystal is studied as a function of temperature. The specially designed ultrafast crystal quenching setup with the cooling rate of 6000 K/s allows to draw conclusions about…

Statistical Mechanics · Physics 2015-05-27 Andrzej Szczepkowicz

Olivine comprises approximately 70 $\%$ by volume of the Earth's upper mantle, making it likely that it controls the mechanical, electrical and seismic properties of the upper mantle. All rocks are composed of crystals separated by grain…

Diffusion of elements in the atmosphere and envelope of a star can drastically alter its surface composition, leading to extreme chemical peculiarities. We consider the case of hot subdwarfs, where surface helium abundances range from…

Solar and Stellar Astrophysics · Physics 2018-02-02 Conor M. Byrne , C. Simon Jeffery , Christopher A. Tout , Haili Hu

Using density-functional theory, we predict that the oxidation of the Ru(0001) surface proceeds via the accumulation of sub-surface oxygen in two-dimensional islands between the first and second substrate layer. This leads locally to a…

Photochemical hazes are important opacity sources in temperate exoplanet atmospheres, hindering current observations from characterizing exoplanet atmospheric compositions. The haziness of an atmosphere is determined by the balance between…

Molecular dynamics simulations were performed to study the dependence of migration behaviours of single helium atoms near tungsten surfaces on the surface orientation and temperature. For W{100} and W{110} surfaces, He atoms can quickly…

Materials Science · Physics 2015-12-09 Xiaoshuang Wang , Zhangwen Wu , Qing Hou

We report surface hardening or crust formation, unlike caking, during drying when a confined porous medium was heated from above using IR radiation. These crusts have higher strength than their closest counterparts such as sandcastles and…

Soft Condensed Matter · Physics 2020-09-04 Navneet Kumar , Jaywant H Arakeri , M S Bobji