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We investigate prestellar core formation and accretion based on three-dimensional hydrodynamic simulations. Our simulations represent local $\sim 1$pc regions within giant molecular clouds where a supersonic turbulent flow converges,…

Solar and Stellar Astrophysics · Physics 2015-06-10 Munan Gong , Eve C. Ostriker

We investigate the question of whether ambipolar diffusion (ion-neutral drift) determines the smallest length and mass scale on which structure forms in a turbulent molecular cloud. We simulate magnetized turbulence in a mostly neutral,…

Astrophysics · Physics 2009-11-13 Jeffrey S. Oishi , Mordecai-Mark Mac Low

Upstream of shocks, the foreshock is filled with hot ions. When these ions are concentrated and thermalized around a discontinuity, a diamagnetic cavity bounded by compressional boundaries, referred to as a foreshock transient, forms.…

Space Physics · Physics 2020-09-25 Xin An , Terry Z. Liu , Jacob Bortnik , Adnane Osmane , Vassilis Angelopoulos

We report on the temporally and spatially resolved detection of the precursory stages that lead to the formation of an unmagnetized, supercritical collision-less shock in a laser-driven laboratory experiment. The measured evolution of the…

High Energy Astrophysical Phenomena · Physics 2015-06-15 H Ahmed , ME Dieckmann , L Romagnani , D Doria , G Sarri , M Cherchez , E Ianni , I Kourakis , AL Giesecke , M Notley , R Prasad , K Quinn , O Willi , M Borghesi

We systematically perform hydrodynamics simulations of 20 km s^-1 converging flows of the warm neutral medium (WNM) to calculate the formation of the cold neutral medium (CNM), especially focusing on the mean properties of the multiphase…

We numerically model evolution of magnetic fields inside a neutron star under the influence of ambipolar diffusion in the weak-coupling mode in the one-fluid MHD approximation. Our simulations are three-dimensional and performed in…

High Energy Astrophysical Phenomena · Physics 2022-11-09 Andrei P. Igoshev , Rainer Hollerbach

The most common method to characterize the electrical response of a nanofluidic system is through its steady-state current-voltage response. In Part I, we demonstrated that this current-voltage response depends on the geometry, the layout…

Mesoscale and Nanoscale Physics · Physics 2025-06-11 Ramadan Abu-Rjal , Yoav Green

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 numerically reproduce the density profiles for filaments that are in magnetohydrostatic and pressure equilibrium with their surroundings obtained in Tomisaka (2014) and show that these equilibria are dynamically stable. If the effect of…

Astrophysics of Galaxies · Physics 2016-11-30 C. A. Burge , S. Van Loo , S. A. E. G. Falle , T. W. Hartquist

Supersonic isothermal turbulence establishes a network of transient dense shocks that sweep up material and have a density profile described by balance between ram pressure of the background fluid versus the magnetic and gas pressure…

Astrophysics of Galaxies · Physics 2018-08-08 Philip Mocz , Blakesley Burkhart

Following an approach initially outlined by McKee & Holliman, we investigate the structure and stability of dense, starless molecular cloud cores. We model those as spherical clouds in hydrostatic equilibrium and supported against gravity…

Astrophysics · Physics 2007-05-23 J. Kauffmann , F. Bertoldi

We present an idealized, spherical model of the evolution of a magnetized molecular cloud due to ambipolar diffusion. This model allows us to follow the quasi-static evolution of the cloud's core prior to collapse and the subsequent…

Astrophysics · Physics 2009-10-30 P. N. Safier , C. F. McKee , S. W. Stahler

A magnetohydrodynamic model of a steady, transverse C-type shock in a dense molecular cloud is presented. A complete gas-grain chemical network is taken into account: the gas-phase chemistry, the adsorption of gas species on dust grains,…

Astrophysics of Galaxies · Physics 2018-06-12 A. V. Nesterenok

C-type shocks are believed to be ubiquitous in turbulent molecular clouds thanks to ambipolar diffusion. We investigate whether the drag instability in 1D isothermal C-shocks, inferred from the local linear theory of Gu & Chen, can appear…

Astrophysics of Galaxies · Physics 2022-08-23 Pin-Gao Gu , Che-Yu Chen , Emma Shen , Chien-Chang Yen , Min-Kai Lin

We investigate a specific reaction-diffusion system that admits a monostable pulled front propagating at constant critical speed. When a small parameter changes sign, the stable equilibrium behind the front destabilizes, due to essential…

Analysis of PDEs · Mathematics 2021-10-07 Louis Garénaux

We present a numerical simulation of the dynamical collapse of a nonrotating magnetic molecular cloud core and follow the core's evolution through the formation of a central point mass and its subsequent growth to a 1 solar-mass protostar.…

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

We present the results of a numerical simulation in which star formation proceeds from an initially unbound molecular cloud core. The turbulent motions, which dominate the dynamics, dissipate in shocks leaving a quiescent region which…

Astrophysics · Physics 2009-11-10 Paul C. Clark , Ian A. Bonnell

The plasma of the lower solar atmosphere consists of mostly neutral particles, whereas the upper solar atmosphere is mostly ionised particles and electrons. A shock that propagates upwards in the solar atmosphere therefore undergoes a…

Solar and Stellar Astrophysics · Physics 2020-05-27 Ben Snow , Andrew Hillier

We investigate the propagation of a shock wave into a warm neutral medium and cold neutral medium by one-dimensional hydrodynamic calculations with detailed treatment of thermal and chemical processes. Our main result shows that thermal…

Astrophysics · Physics 2009-10-31 Hiroshi Koyama , Shu-Ichiro Inutsuka

We simulate fragmentation and gravitational collapse of cold, magnetized molecular clouds. We explore the nonlinear development of an instability mediated by ambipolar diffusion, in which the collapse rate is intermediate to fast…

Astrophysics · Physics 2009-10-31 R. Indebetouw , E. G. Zweibel