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Aims. We aim to investigate whether a multilayer ice model can be as successful as a bulk ice model in reproducing the observed abundances of various deuterated gas-phase species toward starless cores. Methods. We calculate abundances for…

Astrophysics of Galaxies · Physics 2016-06-08 O. Sipilä , P. Caselli , V. Taquet

Grain growth during star formation affects the physical and chemical processes in the evolution of star-forming clouds. We investigate the origin of the millimeter (mm)-sized grains recently observed in Class I protostellar envelopes. We…

Solar and Stellar Astrophysics · Physics 2016-06-14 Yi Hang Valerie Wong , Hiroyuki Hirashita , Zhi-Yun Li

Astrochemical models are essential to bridge the gap between the timescales of reactions, experiments, and observations. Ice chemistry in these models experiences a large computational complexity as a result of the many parameters required…

Astrophysics of Galaxies · Physics 2026-02-18 Tobias M. Dijkhuis , Thanja Lamberts , Serena Viti , Herma M. Cuppen

We investigate the impact of dust-induced gas fragmentation on the formation of the first low-mass, metal-poor stars (< 1Msun) in the early universe. Previous work has shown the existence of a critical dust-to-gas ratio, below which dust…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Alexander P. Ji , Anna Frebel , Volker Bromm

HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous…

Astrophysics of Galaxies · Physics 2015-06-19 Dawn Graninger , Eric Herbst , Karin I. Oberg , Anton I. Vasyunin

Interstellar dust grains can be spun up by radiative torques, and the resulting centrifugal force may be strong enough to disrupt large dust grains. We examine the effect of this rotational disruption on the evolution of grain size…

Astrophysics of Galaxies · Physics 2020-04-08 Hiroyuki Hirashita , Thiem Hoang

Up to 90% of the chemical reactions during star formation occurs on ice surfaces, probably including the formation of complex organics. Only the most abundant ice species are however observed directly by infrared spectroscopy. This study…

Solar and Stellar Astrophysics · Physics 2015-05-13 Karin I. Oberg , Sandrine Bottinelli , Ewine F. van Dishoeck

We present high resolution ($1024^3$) simulations of super-/hyper-sonic isothermal hydrodynamic turbulence inside an interstellar molecular cloud (resolving scales of typically 20 -- 100 AU), including a multi-disperse population of dust…

Astrophysics of Galaxies · Physics 2018-12-19 Lars Mattsson , Akshay Bhatnagar , Fred A. Gent , Beatriz Villarroel

We present a method to include the evolution of the grain size and grain opacity $\kappa_\mathrm{gr}$ in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size…

Earth and Planetary Astrophysics · Physics 2015-06-22 Chris W. Ormel

Cold molecular clouds are the birthplaces of stars and planets, where dense cores of gas collapse to form protostars. The dust mixed in these clouds is thought to be made of grains of an average size of 0.1 micrometer. We report the…

Astrophysics of Galaxies · Physics 2011-10-20 Laurent Pagani , Jürgen Steinacker , Aurore Bacmann , Amelia Stutz , Thomas Henning

Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d ice survey, complimented with data sets on ices in cloud cores and high-mass…

Atoms and molecules, and in particular CO, are important coolants during the evolution of interstellar star-forming gas clouds. The presence of dust grains, which allow many chemical reactions to occur on their surfaces, strongly impacts…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. Hocuk , S. Cazaux , M. Spaans

Context. Millimetric observations have measured high degrees of molecular deuteration in several species seen around low-mass protostars. The Herschel Space Telescope, launched in 2009, is now providing new measures of the deuterium…

We apply the time evolution of grain size distributions by accretion and coagulation found in our previous work to the modelling of the wavelength dependence of interstellar linear polarization. We especially focus on the parameters of the…

Astrophysics of Galaxies · Physics 2015-06-22 Nikolai V. Voshchinnikov , Hiroyuki Hirashita

Hot accretion disks around massive protostars provide a unique opportunity to study ice-free silicate grains that cannot be investigated in protoplanetary disks. We conduct a self-consistent investigation into grain-size evolution and its…

Solar and Stellar Astrophysics · Physics 2025-08-26 Ryota Yamamuro , Kei E. I. Tanaka , Satoshi Okuzumi

We investigate shattering and coagulation of dust grains in turbulent interstellar medium (ISM). The typical velocity of dust grain as a function of grain size has been calculated for various ISM phases based on a theory of grain dynamics…

Astrophysics · Physics 2009-11-13 Hiroyuki Hirashita , Huirong Yan

Dust grains coagulate into larger aggregates in dense gas. This changes their size distribution and possibly affects the thermal evolution of star-forming clouds. We here investigate dust coagulation in collapsing pre-stellar cores with…

Astrophysics of Galaxies · Physics 2015-05-13 Hiroyuki Hirashita , Kazuyuki Omukai

Shattering of dust grains in the interstellar medium is a viable mechanism of small grain production in galaxies. We examine the robustness or uncertainty in the theoretical predictions of shattering. We identify $P_1$ (the critical…

Astrophysics of Galaxies · Physics 2015-06-15 Hiroyuki Hirashita , Hiroshi Kobayashi

The properties of interstellar grains, such as grain size distribution and grain porosity, are affected by interstellar processing, in particular, coagulation and shattering, which take place in the dense and diffuse interstellar medium…

Astrophysics of Galaxies · Physics 2021-01-13 Hiroyuki Hirashita , Vladimir B. Il'in , Laurent Pagani , Charlène Lefèvre

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…

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