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Computational models of interstellar gas-grain chemistry have historically adopted a single dust-grain size of 0.1 micron, assumed to be representative of the size distribution present in the interstellar medium. Here, we investigate the…

Astrophysics of Galaxies · Physics 2016-02-03 Tyler Pauly , Robin T. Garrod

In this work we investigate the effects of ion accretion and size-dependent dust temperatures on the abundances of both gas-phase and grain-surface species. While past work has assumed a constant areal density for icy species, we show that…

Astrophysics of Galaxies · Physics 2016-06-23 J. X. Ge , J. H. He , Aigen Li

Species abundances in the interstellar medium (ISM) strongly depend on the chemistry occurring at the surfaces of the dust grains. To describe the complexity of the chemistry, various numerical models have been constructed. In most of these…

Astrophysics of Galaxies · Physics 2018-07-04 Wasim Iqbal , Valentine Wakelam

Context. Interstellar surface chemistry is a complex process that occurs in icy layers accumulated onto grains of different sizes. Efficiency of surface processes often depends on the immediate environment of adsorbed molecules. Aims. We…

Astrophysics of Galaxies · Physics 2024-07-31 Juris Kalvāns , Aija Kalniņa , Kristaps Veitners

Grain surface chemistry is key to the composition of protoplanetary disks around young stars. The temperature of grains depends on their size. We evaluate the impact of this temperature dependence on the disk chemistry. We model a…

Astrophysics of Galaxies · Physics 2021-10-13 S. Gavino , A. Dutrey , V. Wakelam , S. Guilloteau , J. Kobus , S. Wolf , W. Iqbal , E. Di Folco , E. Chapillon , V. Piétu

The dust grain size distribution (GSD) likely varies significantly across star-forming environments in the Universe, but its impact on star formation remains unclear. This ambiguity arises because the GSD interacts non-linearly with…

Astrophysics of Galaxies · Physics 2024-10-08 Nadine H. Soliman , Philip F. Hopkins , Michael Y. Grudić

Context. Cosmic ray particles that hit interstellar grains in dark molecular cores may induce whole-grain heating. The high temperature of a CR-heated grain allows energy barriers for bulk diffusion and reactions to be overcome.…

Astrophysics of Galaxies · Physics 2014-12-17 Juris Kalvans

We developed a chemical network for modeling the chemistry and non-ideal MHD effects from the collapsing dense molecular clouds to protostellar disks. First, we re-formulated the cosmic-ray desorption rate by considering the variations of…

Solar and Stellar Astrophysics · Physics 2018-05-16 Bo Zhao , Paola Caselli , Zhi-Yun Li

The physical conditions in a collapsing cloud can be traced by observations of molecular lines. To correctly interpret these observations the abundance distributions of the observed species need to be derived. The chemistry in a collapsing…

Solar and Stellar Astrophysics · Physics 2009-11-13 R. J. van Weeren , C. Brinch , M. R. Hogerheijde

Observations of gaseous complex organic molecules (COMs) in cold starless and prestellar cloud cores require efficient desorption of the COMs and their parent species from icy mantles on interstellar grains. With a simple astrochemical…

Astrophysics of Galaxies · Physics 2022-07-04 Juris Kalvāns , Kedron Silsbee

Grain growth by the accretion of metals in interstellar clouds (called `grain growth') could be one of the dominant processes that determine the dust content in galaxies. The importance of grain size distribution for the grain growth is…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Hiroyuki Hirashita , Tzu-Ming Kuo

We study the changes in physical and chemical conditions during the collapse of a pre--protostellar core, starting from initial conditions appropriate to a dense molecular cloud and proceeding to the ``completely depleted'' limit. We follow…

Astrophysics · Physics 2009-11-10 D. R. Flower , G. Pineau des Forets C. M. Walmsley

The formation of molecular hydrogen in the interstellar medium takes place on the surfaces of dust grains. Hydrogen molecules play a role in gas-phase reactions that produce other molecules, some of which serve as coolants during…

Astrophysics · Physics 2009-11-13 Azi Lipshtat , Ofer Biham

Non-thermal desorption of ices on interstellar grains is required to explain observations of molecules that are not synthesized efficiently in the gas phase in cold dense clouds. Perhaps the most important non-thermal desorption mechanism…

Astrophysics of Galaxies · Physics 2021-12-08 O. Sipilä , K. Silsbee , P. Caselli

The first hydrostatic core (FHSC) phase is a brief stage in the protostellar evolution that is difficult to detect. Our goal is to characterize the chemical evolution of gas and dust during the formation of the FHSC. Moreover, we are…

The question, what is the role of freeze-out of chemical species in determining the molecular abundances in the interstellar gas is a matter of debate. We investigate a theoretical case of a dense interstellar molecular cloud core by…

Astrophysics of Galaxies · Physics 2018-03-14 Juris Kalvans , Ivar Shmeld

We model the effect of grain size distribution in a galaxy on the evolution of CO and H$_2$ abundances. The formation and dissociation of CO and H$_2$ in typical dense clouds are modelled in a manner consistent with the grain size…

Astrophysics of Galaxies · Physics 2023-05-10 Hiroyuki Hirashita

The standard model of cosmic ray heating-induced desorption of interstellar ices is based on a continuous representation of the sporadic desorption of ice mantle components from classical (0.1 micron) dust grains. This has been re-evaluated…

Solar and Stellar Astrophysics · Physics 2022-08-17 Jonathan M. C. Rawlings

Context. Dust grains in circumstellar envelopes are likely to have a spread-out temperature distribution. Aims. To investigate how trends in temperature distribution between small and large grains affect the hot corino chemistry of complex…

Astrophysics of Galaxies · Physics 2024-12-18 Juris Kalvans , Juris Freimanis

Abundances and partitioning of ices and gases produced by gas-grain chemistry are governed by adsorption and desorption on grains. Understanding astrophysical observations rely on laboratory measurements of adsorption and desorption rates…

Astrophysics of Galaxies · Physics 2021-02-22 Carine Laffon , Daniel Ferry , Olivier Grauby , Philippe Parent
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