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We introduce a method for calculating the probability density function (PDF) of a turbulent density field in three dimensions using only information contained in the projected two-dimensional column density field. We test the method by…

Astrophysics of Galaxies · Physics 2015-05-18 Christopher M. Brunt , Christoph Federrath , Daniel J. Price

Magnetic fields are dynamically important in the diffuse interstellar medium. Understanding how gravitationally bound, star-forming clouds form requires modeling of the fields in a self-consistent, supernova-driven, turbulent, magnetized,…

Astrophysics of Galaxies · Physics 2022-02-16 Juan C. Ibáñez-Mejía , Mordecai-Mark Mac Low , Ralf S. Klessen

We present results from two-dimensional numerical simulations of a supersonic turbulent flow in the plane of the galactic disk, incorporating shear, thresholded and discrete star formation (SF), self-gravity, rotation and magnetic fields. A…

Astrophysics · Physics 2009-10-28 T. Passot , E. Vazquez-Semadeni , A. Pouquet

The Herschel Gould Belt Survey showed that stars form in dense filaments in nearby molecular clouds. Recent studies suggest that massive filaments are bound by the slow shocks caused by accretion flows onto the filaments. The slow shock is…

Astrophysics of Galaxies · Physics 2023-10-26 Daisei Abe , Tsuyoshi Inoue , Shu-ichiro Inutsuka

We investigate the roles of magnetic fields and ambipolar diffusion during prestellar core formation in turbulent giant molecular clouds (GMCs), using three-dimensional numerical simulations. Our simulations focus on the shocked layer…

Solar and Stellar Astrophysics · Physics 2015-06-19 Che-Yu Chen , Eve C. Ostriker

We obtain self-similar solutions that describe the gravitational collapse of nonrotating, isothermal, magnetic molecular cloud cores. We use simplifying assumptions but explicitly include the induction equation, and the semianalytic…

Astrophysics · Physics 2009-10-30 Ioannis Contopoulos , Glenn E. Ciolek , Arieh Konigl

We present N-PDFs of 29 Galactic regions obtained from Herschel imaging at high angular resolution, covering diffuse and quiescent clouds, and those showing low-, intermediate-, and high-mass star formation (SF), and characterize the cloud…

The effects of ambipolar diffusion on the linear stability of weakly ionised accretion discs are examined. Earlier work on this topic has focused on axial magnetic fields and perturbation wavenumbers. We consider here more general field and…

Astrophysics · Physics 2009-11-10 Matthew W. Kunz , Steven A. Balbus

The amplification of magnetic fields in a highly conducting fluid is studied numerically. During growth, the magnetic field is spatially intermittent: it does not uniformly fill the volume, but is concentrated in long thin folded…

Chaotic Dynamics · Physics 2009-11-10 A. A. Schekochihin , S. C. Cowley , J. L. Maron , J. C. McWilliams

Ambipolar diffusion (AD) is believed to be a crucial process for redistributing magnetic flux in the dense molecular gas that occurs in regions of star formation. We carry out numerical simulations of this process in regions of low…

Solar and Stellar Astrophysics · Physics 2015-05-30 Pak Shing Li , Christopher F. McKee , Richard I. Klein

The shape of the probability distribution function (PDF) of molecular clouds is an important ingredient for modern theories of star formation and turbulence. Recently, several studies have pointed out observational difficulties with…

Astrophysics of Galaxies · Physics 2015-10-07 Blakesley Burkhart , Min-Young Lee , Claire Murray , Snezana Stanimirovic

We used magnetohydrodynamic (MHD) simulations of interstellar turbulence to study the probability distribution functions (PDFs) of increments of density, velocity, and magnetic field. We found that the PDFs are well described by a Tsallis…

Astrophysics of Galaxies · Physics 2011-08-04 A. Esquivel , A. Lazarian

We present a parameter study of simulations of fragmentation regulated by gravity, magnetic fields, ambipolar diffusion, and nonlinear flows. The thin-sheet approximation is employed with periodic lateral boundary conditions, and the…

Astrophysics · Physics 2011-12-20 Shantanu Basu , Glenn E. Ciolek , Wolf Dapp , James Wurster

We numerically study the volume density probability distribution function (n-PDF) and the column density probability distribution function (Sigma-PDF) resulting from thermally bistable turbulent flows. We analyze three-dimensional…

Astrophysics of Galaxies · Physics 2015-06-12 Adriana Gazol , Jongsoo Kim

The gravitational instability of a filamentary molecular cloud in non-ideal magnetohydrodynamics is investigated. The filament is assumed to be in hydrostatic equilibrium. We add the effect of ambipolar diffusion to the filament which is…

Astrophysics of Galaxies · Physics 2016-12-21 Mohammad Hosseinirad , Kazem Naficy , Shahram Abbassi , Mahmood Roshan

Thermal instability is one of the most important processes in the formation of clumpy substructure in magnetic molecular clouds. On the other hand, ambipolar diffusion, or ion-neutral friction, has long been thought to be an important…

Astrophysics · Physics 2009-11-10 Mohsen Nejad-Asghar , Jamshid Ghanbari

Observations indicate that dense molecular filamentary clouds are sites of star formation. The filament width determines the most unstable scale for self-gravitational fragmentation and influences the stellar mass. Therefore, constraining…

Astrophysics of Galaxies · Physics 2025-05-09 Daisei Abe , Tsuyoshi Inoue , Shu-ichiro Inutsuka , Doris Arzoumanian

We present a set of numerical experiments designed to systematically investigate how turbulence and magnetic fields influence the morphology, energetics, and dynamics of filaments produced in wind-cloud interactions. We cover 3D…

Astrophysics of Galaxies · Physics 2017-12-06 Wladimir Banda-Barragán , Christoph Federrath , Roland Crocker , Geoffrey Bicknell

We investigate differences in the molecular abundances between magnetically super- and sub-critical prestellar cores, performing three-dimensional non-ideal magnetohydrodynamical (MHD) simulations with varying densities and magnetic field…

Astrophysics of Galaxies · Physics 2019-07-17 Felix D. Priestley , James Wurster , Serena Viti

We study the linear evolution of small perturbations in self-gravitating fluid systems with magnetic fields. We consider wave-like perturbations to nonuniform filamentary and sheet-like hydrostatic equilibria in the presence of a uniform…

Astrophysics · Physics 2015-06-24 Curtis S. Gehman , Fred C. Adams , Richard Watkins