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The 4.62 micron absorption band, observed along the line-of-sight towards various young stellar objects, is generally used as a qualitative indicator for energetic processing of interstellar ice mantles. This interpretation is based on the…

Astrophysics · Physics 2009-11-10 F. A. van Broekhuizen , J. V. Keane , W. A. Schutte

Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N2, with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear…

Interstellar ices are layers of molecules deposited on !ne dust grains in dark and dense molecular cloud cores. Subsurface ice has been considered in a few astrochemical models, which have shown that it can be of great importance. The aim…

Instrumentation and Methods for Astrophysics · Physics 2013-08-26 Juris Kalvans

Glycolaldehyde (HOCH2CHO) is the most straightforward sugar detected in the Interstellar Medium (ISM) and participates in the formation pathways of molecules fundamental to life, red such as ribose and derivatives. Although detected in…

Astrophysics of Galaxies · Physics 2023-02-07 Mateus A. M. Paiva , Sergio Pilling , Edgar Mendoza , Breno R. L. Galvão , Heitor A. De Abreu

Diffusion of species in icy dust grain mantles is a fundamental process that shapes the chemistry of interstellar regions; yet measurements of diffusion in interstellar ice analogs are scarce. Here we present measurements of CO diffusion…

Astrophysics of Galaxies · Physics 2018-01-24 Ilsa R. Cooke , Karin I. Öberg , Edith C. Fayolle , Zoe Peeler , Jennifer B. Bergner

Advanced telescopes, such as ALMA and JWST, are likely to show that the chemical universe may be even more complex than currently observed, requiring astrochemical modelers to improve their models to account for the impact of new data.…

Astrophysics of Galaxies · Physics 2017-08-07 E M Penteado , C Walsh , H M Cuppen

We study the formation of water and methanol in the dense cloud conditions to find the dependence of its production rate on the binding energies, reaction mechanisms, temperatures, and grain site number. We wish to find the effective grain…

Astrophysics · Physics 2009-11-13 Ankan Das , Kinsuk Acharyya , Sonali Chakrabarti , Sandip Kumar Chakrabarti

The mobility of lighter species on the surface of interstellar dust grains plays a crucial role in forming simple through complex molecules. Carbon monoxide is one of the most abundant molecules, its surface diffusion on the grain surface…

Astrophysics of Galaxies · Physics 2022-03-30 Kinsuk Acharyya

Models play an important role in our understanding of the global structure of the solar wind and its interaction with the interstellar medium. A critical ingredient in many types of models are the charge-exchange collisions between ions and…

Solar and Stellar Astrophysics · Physics 2020-06-30 M. Bzowski , J. Heerikhuisen

We describe an overall picture of galactic-scale star formation. Recent high-resolution magneto-hydrodynamical simulations of two-fluid dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds…

Astrophysics of Galaxies · Physics 2015-07-29 Shu-ichiro Inutsuka , Tsuyoshi Inoue , Kazunari Iwasaki , Takashi Hosokawa

Star formation depends on the available gaseous "fuel" as well as galactic environment, with higher specific star formation rates where gas is predominantly molecular and where stellar (and dark matter) densities are higher. The partition…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Eve C. Ostriker

In the currently-accepted model for star formation out of the interstellar gas in galaxies, the basic construction material is assumed to be large clouds of atomic hydrogen (HI). These clouds are thought to form higher-density complexes of…

Astrophysics · Physics 2007-05-23 Ronald J. Allen

The temperatures of interstellar dust grains are analyzed using stochastic simulations, taking into account the grain composition and size and the discreteness of the photon flux. [...] The distribution of grain temperatures is calculated…

Astrophysics · Physics 2007-09-21 Kobi Horn , Hagai B. Perets , Ofer Biham

Chemical reactions on dust grains are of crucial importance in interstellar chemistry because they produce molecular hydrogen and various organic molecules. Due to the submicron size of the grains and the low flux, the surface populations…

Astrophysics · Physics 2009-11-10 Azi Lipshtat , Ofer Biham

Icy grain mantles are commonly observed through infrared spectroscopy toward dense clouds, cloud cores, protostellar envelopes and protoplanetary disks. Up to 80% of the available oxygen, carbon and nitrogen are found in such ices; the most…

Star formation in galaxies is regulated by the heating and cooling in the interstellar medium. In particular, the processing of molecular gas into stars will depend strongly on the ratio of gas heating to gas cooling in the neutral gas…

Deposition of water on aerosol particles contributes to ice cloud formation in the atmosphere with implications for the water cycle and climate on Earth. The heterogeneous ice nucleation process is influenced by physico-chemical properties…

Chemical Physics · Physics 2013-09-13 Xiangrui Kong , Patrik U. Andersson , Erik S. Thomson , Jan B. C. Pettersson

We propose a simple theoretical model for star formation in which the local star formation rate in a galaxy is determined by three factors. First, the interplay between the interstellar radiation field and molecular self-shielding…

Astrophysics of Galaxies · Physics 2011-02-11 Mark R. Krumholz , Christopher F. McKee , Jason Tumlinson

In this work, we conducted molecular dynamics simulations to study the fracture mechanism of ice crystals in a bulk phase and at ice-ice interfaces at the atomistic scale. We show that there exists a narrow disordered interfacial layer…

Chemical Physics · Physics 2019-07-23 A. Afshar , J. Zhong , D. S. Thompson , D. Meng

Using all-atomic molecular dynamics(MD) simulations, we show that various substrates could induce interfacial water (IW) to form the same ice-like oxygen lattice but different hydrogen polarity order, and regulate the heterogeneous ice…

Computational Physics · Physics 2020-02-19 Mingzhe Shao , Chuanbiao Zhang , Conghai Qi , Chunlei Wang , Jianjun Wang , Fangfu Ye , Xin Zhou