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Using local 3D MHD simulations, we investigate ways in which galactic turbulence associated with the magnetorotational instability (MRI) may influence the formation and properties of GMCs. Our disk models are vertically stratified and…

Astrophysics · Physics 2009-11-10 Woong-Tae Kim , Eve C. Ostriker , James M. Stone

All stars are born in molecular clouds, and most in giant molecular clouds (GMCs), which thus set the star formation activity of galaxies. We first review their observed properties, including measures of mass surface density, Sigma, and…

Astrophysics of Galaxies · Physics 2015-06-12 Jonathan C. Tan , Suzanne N. Shaske , Sven Van Loo

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

We discuss the lifetimes and evolution of clumps and cores formed as turbulent density fluctuations in nearly isothermal molecular clouds. In the non-magnetic case, clumps are unlikely to reach a hydrostatic state, and instead are expected…

Molecular clouds exhibit lognormal probability density functions (PDF) of mass densities, which are thought to arise as a consequence of isothermal, supersonic turbulence. Star formation is then widely assumed to occur in perturbations in…

Astrophysics of Galaxies · Physics 2018-10-10 Evan Scannapieco , Mohammadtaher Safarzadeh

Galaxies comprise intricate networks of interdependent processes which together govern their evolution. Central among these are the multiplicity of feedback channels, which remain incompletely understood. One outstanding problem is the…

Astrophysics of Galaxies · Physics 2023-12-11 Brent Tan , Drummond B. Fielding

Giant molecular clouds contain supersonic turbulence and simulations of magnetohydrodynamic turbulence show that these supersonic motions decay in roughly a crossing time, which is less than the estimated lifetimes of molecular clouds. Such…

Astrophysics of Galaxies · Physics 2012-07-13 A. Pon , D. Johnstone , M. J. Kaufman

The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252…

Astrophysics of Galaxies · Physics 2024-06-28 Alex Lv , Lile Wang , Renyue Cen , Luis C. Ho

The ISM is governed by supersonic turbulence on a range of scales. We use this to develop a rigorous excursion-set model for the formation and time evolution of dense gas structures (GMCs, massive clumps, and cores). Supersonic turbulence…

Astrophysics of Galaxies · Physics 2013-07-02 Philip F. Hopkins

The observed rapid onset of star formation in molecular clouds requires rapid formation of dense fragments which can collapse individually before being overtaken by global gravitationally-driven flows. Many previous investigations have…

Astrophysics · Physics 2009-11-13 F. Heitsch , L. Hartmann , A. Burkert , ;

(Abridged) We explore the chemistry of the most abundant C, O, S, and N bearing species in molecular clouds, in the context of the IRAM 30 m Large Programme Gas phase Elemental abundances in Molecular Clouds (GEMS). In this work, we aim to…

We describe a numerical implementation of star formation in disk galaxies, in which the conversion of cooling gas to stars in the multiphase interstellar medium is governed by the rate at which molecular clouds are formed and destroyed. In…

Astrophysics · Physics 2008-11-26 C. M. Booth , T. Theuns , T. Okamoto

We present results of large-scale three-dimensional simulations of weakly magnetized supersonic turbulence at grid resolutions up to 1024^3 cells. Our numerical experiments are carried out with the Piecewise Parabolic Method on a Local…

Astrophysics of Galaxies · Physics 2009-08-13 Alexei G. Kritsuk , Sergey D. Ustyugov , Michael L. Norman , Paolo Padoan

We present a detailed study of the collapse of molecular cloud cores using high resolution 3D adaptive mesh refinement (AMR) numerical simulations. In this first in a series of investigations our initial conditions consists of spherical…

Astrophysics · Physics 2009-11-10 Robi Banerjee , Ralph E. Pudritz , Lindsay Holmes

We have performed smoothed particle radiation magnetohydrodynamics (SPRMHD) simulations of the collapse of rotating, magnetised molecular cloud cores to form protostars. The calculations follow the formation and evolution of the first…

Solar and Stellar Astrophysics · Physics 2015-06-17 Matthew R. Bate , Terrence S. Tricco , Daniel J. Price

This is the first attempt to construct detailed X-ray spectra of clusters of galaxies from the results of high-resolution hydrodynamic simulations and simulate X-ray observations in order to study velocity fields of the intracluster medium…

Astrophysics · Physics 2009-11-10 Yutaka Fujita , Tomoaki Matsumoto , Keiichi Wada , Tae Furusho

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

Astrophysics · Physics 2009-11-13 P. Hennebelle , R. Banerjee , E. Vazquez-Semadeni , R. Klessen , E. Audit

Using smoothed particle hydrodynamics in combination with the special-purpose hardware device GRAPE, we follow the fragmentation process and dynamical evolution in the interior of molecular clouds until most of the gas is converted to form…

Astrophysics · Physics 2007-05-23 Ralf S. Klessen , Andreas Burkert

Two scenarios have been proposed for evolution of star forming cores: gravitational fragmentation of larger structures and coalescence of smaller entities which are formed from some instabilities. Here, we turn our attention to the latter…

Astrophysics of Galaxies · Physics 2015-05-18 M. Nejad-Asghar

We performed simulations of self-gravitating hydrodynamic turbulence to model the formation of filaments, clumps and cores in molecular clouds. We find that when the mass on the initial computational grid is comparable to the Jeans mass,…

Astrophysics · Physics 2007-05-23 David A. Tilley , Ralph E. Pudritz , James Wadsley