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We study the interaction of atomic and molecular hydrogen with a surface of tholin, a man-made polymer considered to be an analogue of aerosol particles present in Titan's atmosphere, using thermal programmed desorption at low temperatures…

Earth and Planetary Astrophysics · Physics 2010-10-08 Ling Li , Hui Zhao , Gianfranco Vidali , Yechiel Frank , Ingo Lohmar , Hagai B. Perets , Ofer Biham

The immiscibility of hydrogen-helium mixture under the temperature and pressure conditions of planetary interiors is crucial for understanding the structures of gas giant planets (e.g., Jupiter and Saturn). While the experimental probe at…

The behaviour of molecules in space is to a large extent governed by where they freeze out or sublimate. The molecular binding energy is thus an important parameter for many astrochemical studies. This parameter is usually determined with…

Astrophysics of Galaxies · Physics 2022-10-05 Torben Villadsen , Niels F. W. Ligterink , Mie Andersen

Hydrogen, being the most abundant element, is the driver of many if not most reactions occurring on interstellar dust grains. In hydrogen atom addition reactions, the rate is usually determined by the surface kinetics of the hydrogen atom…

Instrumentation and Methods for Astrophysics · Physics 2017-12-27 Jiao He , Shahnewaj M. Emtiaz , Gianfranco Vidali

We describe a mechanism that explains the formation of hydrocarbons and hydrocarbyls from hydrogenated graphene/graphite; hard C-C bonds are weakened and broken by the synergistic effect of chemisorbed hydrogen and high temperature…

Mesoscale and Nanoscale Physics · Physics 2014-08-22 Jose I. Martinez , Jose A. Martin-Gago , Jose Cernicharo , Pedro L. de Andres

Hydrogen grain boundary (GB) trapping is widely accepted as the main cause for hydrogen induced intergranular failure. Several studies were conducted to unveil the role of GBs on hydrogen transport; however, a clear understanding is yet to…

Materials Science · Physics 2024-12-30 Abdelrahman Hussein , Byungki Kim , Tom Depover , Kim Verbeken

Context: B[e] supergiants are known to have non-spherical winds, and the existence of disks that are neutral in hydrogen close to their stellar surface has been postulated. A suitable mechanism to produce non-spherical winds seems to be…

Astrophysics · Physics 2009-11-11 Michaela Kraus

Glycoaldehyde, ethylene glycol, and methyl formate are complex organic molecules that have been observed in dark molecular clouds. Because there is no efficient gas-phase route to produce these species, it is expected that a low-temperature…

Solar and Stellar Astrophysics · Physics 2020-02-12 M. A. J. Simons , T. Lamberts , H. M. Cuppen

The aim of the presented work is to analyze the impact of experimentally evaluated reactions of hydrogen abstraction on surfaces of interstellar grains on the chemical evolution of methanol and its precursors on grains and in the gas phase…

Astrophysics of Galaxies · Physics 2021-03-24 V. A. Sokolova

The recent wave of detections of interstellar aromatic molecules has sparked interest in the chemical behavior of aromatic molecules under astrophysical conditions. In most cases, these detections have been made through chemically related…

Astrophysics of Galaxies · Physics 2021-07-07 April M. Miksch , Annalena Riffelt , Ricardo Oliveira , Johannes Kästner , Germán Molpeceres

We have introduced a new method of estimating the electron temperature and density of H II regions by using single dish observations. In this method, multiple hydrogen radio recombination lines of different bands are computed under the…

Solar and Stellar Astrophysics · Physics 2019-11-14 F. -Y. Zhu , Q. -F. Zhu , J. -Z. Wang , J. -S Zhang

We investigate the role of carbon monoxide ice in the chemical evolution of prestellar cores using astrochemical rate equation models. We constrain the ratios of the binding energies on CO ice and H$_{2}$O ice for a series of adsorbates…

Astrophysics of Galaxies · Physics 2024-08-14 Germán Molpeceres , Kenji Furuya , Yuri Aikawa

Determinations of the primordial helium abundance are used in precision cosmological tests. These require highly accurate He I recombination rate coefficients. Here we reconsider the formation of He I recombination lines in the low-density…

Astrophysics · Physics 2009-11-10 R. P. Bauman , R. L. Porter , G. J. Ferland , K. B. MacAdam

Energy-changing electron-hydrogen atom collisions are crucial to regulating the energy balance in astrophysical and laboratory plasmas and relevant to the formation of stellar atmospheres, recombination in H-II clouds, primordial…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Daniel Vrinceanu , Roberto Onofrio , Hossein R. Sadeghpour

Understanding gas-grain chemistry of deuterium in star-forming objects may help to explain their history and present state. We aim to clarify how processes in ices affect the deuterium fractionation. In this regard, we investigate a…

Astrophysics of Galaxies · Physics 2017-02-01 J. Kalvans , I. Shmeld , J. R. Kalnin , S. Hocuk

Grain boundary (GB) energy is a fundamental property that affects the form of grain boundary and plays an important role to unveil the behavior of polycrystalline materials. With a better understanding of grain boundary energy distribution…

Computational Physics · Physics 2020-02-04 Haoyu Wang , Srikanth Patala , Brian J. Reich

For the first time, we report a unified microscopic-macroscopic Monte Carlo simulation of gas-grain chemistry in cold interstellar clouds in which both the gas-phase and the grain surface chemistry are simulated by a stochastic technique.…

Astrophysics of Galaxies · Physics 2015-06-11 Qiang Chang , Eric Herbst

Context. Level population inversion of hydrogen atoms in ionized gas may lead to stimulated emission of hydrogen recombination lines, and the level populations can in turn be affected by powerful stimulated emissions. Aims. In this work the…

Astrophysics of Galaxies · Physics 2022-09-21 Feng-Yao Zhu , Junzhi Wang , Qing-Feng Zhu , Jiang-Shui Zhang

Recent studies on graphene hydrogenation processes showed that hydrogenation occurs via island growing domains, however how the substrate can affect the hydrogenation dynamics and/or pattern formation has not been yet properly investigated.…

The equation of state for hydrogen and helium is fundamental for studying stars and giant planets. It has been shown that because of interactions at atomic and molecular levels, the behaviour of a mixture of hydrogen and helium cannot be…

Earth and Planetary Astrophysics · Physics 2023-03-29 Saburo Howard , Tristan Guillot