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Numerical studies of the interplanetary "multiple magnetic clouds (Multi-MC)" are performed by a 2.5-dimensional ideal magnetohydrodynamic (MHD) model in the heliospheric meridional plane. Both slow MC1 and fast MC2 are initially emerged…

空间物理 · 物理学 2009-05-08 Ming Xiong , Huinan Zheng , S. T. Wu , Yuming Wang , Shui Wang

This paper investigates the nature of the MHD turbulence excited by the streaming of accelerated cosmic rays in a shock wave precursor. The two recognised regimes (non-resonant and resonant) of the streaming instability are taken into…

天体物理学 · 物理学 2009-11-11 Guy Pelletier , Martin Lemoine , Alexandre Marcowith

Molecular clouds are supersonically turbulent. This turbulence governs the initial mass function and the star formation rate. In order to understand the details of star formation, it is therefore essential to understand the properties of…

星系天体物理 · 物理学 2015-06-17 Adam Ginsburg , Christoph Federrath , Jeremy Darling

We report results of a three dimensional, high resolution (up to 512^3) numerical investigation of supersonic compressible magnetohydrodynamic turbulence. We consider both forced and decaying turbulence. The model parameters are appropriate…

天体物理学 · 物理学 2009-10-30 James M. Stone , Eve C. Ostriker , Charles F. Gammie

We review recent results from numerical simulations and related models of MHD turbulence in the interstellar medium (ISM) and in molecular clouds. We discuss the implications of turbulence for the processes of cloud formation and evolution,…

天体物理学 · 物理学 2007-05-23 E. Vazquez-Semadeni , E. C. Ostriker , T. Passot , C. F. Gammie , J. M. Stone

We explore the structure and statistics of multiphase, magnetized ISM turbulence in the local Milky Way by means of driven periodic box numerical MHD simulations. Using the higher order-accurate piecewise-parabolic method on a local stencil…

星系天体物理 · 物理学 2017-06-19 Alexei G. Kritsuk , Sergey D. Ustyugov , Michael L. Norman

This chapter reviews the nature of turbulence in the Galactic interstellar medium (ISM) and its connections to the star formation (SF) process. The ISM is turbulent, magnetized, self-gravitating, and is subject to heating and cooling…

星系天体物理 · 物理学 2017-03-15 Enrique Vazquez-Semadeni

Observations in polarized emission reveal the existence of large-scale coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization data show that these fields are strongly inclined towards the radial direction, with…

天体物理学 · 物理学 2009-11-13 Oliver Gressel , Udo Ziegler , Detlef Elstner , Günther Rüdiger

Direct numerical simulations of decaying and forced magnetohydrodynamic (MHD) turbulence without and with mean magnetic field are analyzed by higher-order two-point statistics. The turbulence exhibits statistical anisotropy with respect to…

等离子体物理 · 物理学 2009-11-10 Wolf-Christian Mueller , Dieter Biskamp , Roland Grappin

The power spectrum (PS) of the density field in supersonic turbulence is a fundamental quantity that characterizes the statistical properties of the structures formed in compressible flows. It is also widely used to estimate the Mach number…

星系天体物理 · 物理学 2026-05-12 Pierre Dumond , Jérémy Fensch , Gilles Chabrier , Noé Brucy

Magnetic fields have been included in cosmological simulations of galaxy formation only recently, due to advances in numerical techniques and a better understanding of the galaxy formation physics. In this paper, we develop a new subgrid…

星系天体物理 · 物理学 2022-05-13 Yuankang Liu , Michael Kretschmer , Romain Teyssier

We present three-dimensional, nonrelativistic, hydrodynamic simulations of bow shocks in pulsar wind nebulae. The simulations are performed for a range of initial and boundary conditions to quantify the degree of asymmetry produced by…

天体物理学 · 物理学 2008-11-26 M. Vigelius , A. Melatos , S. Chatterjee , B. M. Gaensler , P. Ghavamian

We investigate the conditions of ideal magnetohydrodynamic (MHD) turbulence responsible for the relative orientation between density structures, characterized by their gradient, $\vec{\nabla}\rho$, and the magnetic field, $\vec{B}$, in…

星系天体物理 · 物理学 2017-11-01 Juan D. Soler , Patrick Hennebelle

We present a number of statistical tools for obtaining studying turbulence in molecular clouds and diffuse interstellar medium. For our tests we used of three-dimensional 512 cube compressible MHD isothermal simulations performed for…

天体物理学 · 物理学 2011-02-11 Blakesley Burkhart , D. Falceta-Goncalves , G. Kowal , A. Lazarian

We examine MHD simulations of the propagation of a strong shock wave through the interstellar two-phase medium composed of small-scale cloudlets and diffuse warm neutral medium in two-dimensional geometry. The pre-shock two-phase medium is…

太阳与恒星天体物理 · 物理学 2010-11-30 Tsuyoshi Inoue , Ryo Yamazaki , Shu-ichiro Inutsuka

One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…

星系天体物理 · 物理学 2015-05-13 Hua-bai Li , C. Darren Dowell , Alyssa Goodman , Roger Hildebrand , Giles Novak

We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the…

天体物理学 · 物理学 2007-05-23 Enrique Vazquez-Semadeni

We discuss constraints on the rates of stirring and dissipation of MHD turbulence in molecular clouds. Recent MHD simulations suggest that turbulence in clouds decays rapidly, thus providing a significant source of energy input,…

天体物理学 · 物理学 2009-11-06 Shantanu Basu , Chigurupati Murali

A significative fraction of all massive stars in the Milky Way move supersonically through their local interstellar medium (ISM), producing bow shock nebulae by wind-ISM interaction. The stability of these observed astrospheres around cool…

太阳与恒星天体物理 · 物理学 2021-08-18 D. M. -A. Meyer , A. Mignone , M. Petrov , K. Scherer , P. F. Velazquez , P. Boumis

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…

星系天体物理 · 物理学 2018-08-08 Philip Mocz , Blakesley Burkhart