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MHD turbulence plays a central role in the physics of star-forming molecular clouds and the interstellar medium. I here show that MHD turbulence in molecular clouds must be driven to account for the observed supersonic motions in the…

Astrophysics · Physics 2007-05-23 Mordecai-Mark Mac Low

A fundamental property of molecular clouds is that they are turbulent, but how this turbulence is generated and maintained is unknown. One possibility is that stars forming within the cloud regenerate turbulence via their outflows, winds…

Solar and Stellar Astrophysics · Physics 2018-10-17 Stella S. R. Offner , Yue Liu

We present a systematic analysis of the velocity structure functions (VSFs) of 167 molecular clouds with angular sizes greater than $\sim$176 arcmin$^2$ in three sectors of the Galactic mid-plane. We calculated the 1st- to 3rd-order VSFs…

We numerically investigate the driving of MHD turbulence by gravitational contraction using simulations of an initially spherical, magnetically supercritical cloud core with initially transonic and trans-Alfv\'enic turbulence. We perform a…

Astrophysics of Galaxies · Physics 2024-03-04 Enrique Vázquez-Semadeni , Yue Hu , Siyao Xu , Rubén Guerrero-Gamboa , Alex Lazarian

A pair of nonlinear diffusion equations in Fourier space} is used to study the dynamics of strong Alfv\'en-wave turbulence, from MHD to electron scales. Special attention is paid to the regime of imbalance between the energies of…

Plasma Physics · Physics 2019-12-12 George Miloshevich , Thierry Passot , Pierre-Louis Sulem

Turbulence is the most common state of astrophysical flows. In typical astrophysical fluids, turbulence is accompanied by strong magnetic fields, which has a large impact on the dynamics of the turbulent cascade. Recently, there has been a…

Astrophysics · Physics 2011-05-10 Jungyeon Cho , A. Lazarian , Ethan Vishniac

We perform three dimensional (3D) ideal magnetohydrodynamic (MHD) simulations to study the parametric decay instability of Alfven waves in turbulent plasmas and explore its possible applications in the solar wind. We find that, over a broad…

Space Physics · Physics 2017-06-16 Mijie Shi , Hui Li , Chijie Xiao , Xiaogang Wang

When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfv\'enic MHD…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Jungyeon Cho , A. Lazarian

Using 3D MHD simulation with the effects of radiative cooling/heating, chemical reactions, and thermal conduction, we investigate the formation of molecular cloud in the ISM. We consider the formation of molecular cloud by accretion of the…

Astrophysics of Galaxies · Physics 2015-06-05 Tsuyoshi Inoue , Shu-ichiro Inutsuka

Magnetohydrodynamics (MHD) provides the simplest description of magnetic plasma turbulence in a variety of astrophysical and laboratory systems. MHD turbulence with nonzero cross helicity is often called imbalanced, as it implies that the…

Astrophysics of Galaxies · Physics 2015-05-18 Jean Carlos Perez , Stanislav Boldyrev

We conduct a three-dimensional magnetohydrodynamic (MHD) simulation of the parametric decay instability of Alfv\'en waves and resultant compressible MHD turbulence, which is likely to develop in the solar wind acceleration region. Because…

Solar and Stellar Astrophysics · Physics 2018-06-06 Munehito Shoda , Takaaki Yokoyama

Molecular clouds have broad linewidths suggesting turbulent supersonic motions in the clouds. These motions are usually invoked to explain why molecular clouds take much longer than a free-fall time to form stars. It has classically been…

Astrophysics · Physics 2011-02-11 Mordecai-Mark Mac Low

We examine the idea that diffuse and giant molecular clouds and their substructure form as density fluctuations induced by large scale interstellar turbulence. We do this by investigating the topology of various fields in realistic…

Astrophysics · Physics 2009-10-30 Javier Ballesteros-Paredes , Enrique Vazquez-Semadeni , John Scalo

The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes with a non-potential field structure that are…

Astrophysics · Physics 2009-11-10 S. S. Hasan , A. A. van Ballegoiijen , W. Kalkofen , O. Steiner

Turbulent magnetic field fluctuations observed in the solar wind often maintain a constant magnitude condition accompanied by spherically polarized velocity fluctuations; these signatures are characteristic of large-amplitude Alfv\'{e}n…

Turbulence in astrophysical and space plasmas is dominated by the nonlinear interaction of counterpropagating Alfven waves. Most Alfven wave turbulence theories have been based on ideal plasma models, such as incompressible MHD, for Alfven…

Numerical simulations of dispersive turbulence in magnetized plasmas based on the Hall-MHD description are presented, assuming spatial variations along a unique direction making a prescribed angle with the ambient magnetic field. Main…

Earth and Planetary Astrophysics · Physics 2015-05-18 D. Laveder , L. Marradi , T. Passot , P. L. Sulem

A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures…

Solar and Stellar Astrophysics · Physics 2015-08-19 G. G. Howes

Interstellar gas clouds are often both highly magnetized and supersonically turbulent, with velocity dispersions set by a competition between driving and dissipation. This balance has been studied extensively in the context of gases with…

Astrophysics of Galaxies · Physics 2018-01-19 Yuval Birnboim , Christoph Federrath , Mark Krumholz

A variety of studies of magnetised plasma turbulence invoke theories for the advection of a passive scalar by turbulent fluctuations. Examples include modelling the electron density fluctuations in the interstellar medium, understanding the…

Plasma Physics · Physics 2015-06-23 Joanne Mason , Stanislav Boldyrev , Fausto Cattaneo , Jean Carlos Perez