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The propagation of high-energy cosmic rays through giant molecular clouds constitutes a fundamental process in astronomy and astrophysics. The diffusion of cosmic-rays through these magnetically turbulent environments is often studied…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Marco Fatuzzo , Fulvio Melia , Elizabeth Todd , Fred Adams

We present high resolution simulations of two-fluid (ion-neutral) MHD turbulence with resolutions as large as 512^3. The simulations are supersonic and mildly sub-Alfvenic, in keeping with the conditions present in molecular clouds. Such…

Astrophysics of Galaxies · Physics 2015-06-16 Chad D. Meyer , Dinshaw S. Balsara , Blakesley Burkhart , Alex Lazarian

We describe a method for determining the dispersion of magnetic field vectors about large-scale fields in turbulent molecular clouds. The method is designed to avoid inaccurate estimates of magnetohydrodynamic or turbulent dispersion - and…

This study is motivated by recent observations on ubiquitous interstellar density filaments and guided by modern theories of compressible magnetohydrodynamic (MHD) turbulence. The interstellar turbulence shapes the observed density…

Astrophysics of Galaxies · Physics 2019-08-07 Siyao Xu , Suoqing Ji , A. Lazarian

We investigate, through 2D MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result…

Astrophysics · Physics 2016-08-30 Francesco Miniati , T. W. Jones , Dongsu Ryu

Massive stars disproportionately influence their surroundings. How they form has only started to become clear recently through radiation gas dynamical simulations. However, until now, no simulation has simultaneously included both magnetic…

Solar and Stellar Astrophysics · Physics 2015-03-17 Thomas Peters , Robi Banerjee , Ralf S. Klessen , Mordecai-Mark Mac Low

In diffuse molecular clouds, possible precursors of star-forming clouds, the effect of the magnetic field is unclear. In this work we compare the orientations of filamentary structures in the Polaris Flare, as seen through dust emission by…

Astrophysics of Galaxies · Physics 2016-08-24 G. V. Panopoulou , I. Psaradaki , K. Tassis

We compute the star formation rate (SFR) in molecular clouds (MCs) that originate {\it ab initio} in a new, higher-resolution simulation of supernova-driven turbulence. Because of the large number of well-resolved clouds with…

Astrophysics of Galaxies · Physics 2017-05-10 Paolo Padoan , Troels Haugbølle , Åke Nordlund , Søren Frimann

We study the turbulent velocity dispersion spectra of the coexistent HCN and HCO+ molecular species as a function of length scale in the M17 star-forming molecular cloud. We show that the observed downward shift of the ion's spectrum…

Astrophysics · Physics 2009-11-13 Hua-bai Li , Martin Houde

Under the basic assumption that the observed turbulent motions in molecular clouds are Alfvenic waves or turbulence, we emphasize that the Doppler broadening of molecular line profiles directly measures the velocity amplitudes of the waves…

Astrophysics · Physics 2009-10-28 Taoling Xie

We present three Orion simulations of star cluster formation in a 1000 Msun, turbulent molecular cloud clump, including the effects of radiative transfer, protostellar outflows, and magnetic fields. Our simulations all use self-consistent…

Astrophysics of Galaxies · Physics 2015-06-18 Andrew Myers , Richard Klein , Mark Krumholz , Chris McKee

Observations of nearby molecular clouds detect "shells", which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from…

Astrophysics of Galaxies · Physics 2015-10-07 S. S. R. Offner , H. G. Arce

We present the results of a large suite of three-dimensional (3D) models of the collapse of magnetic molecular cloud cores using the adaptive mesh refinement (AMR) code Enzo2.2 in the ideal magnetohydrodynamics (MHD) approximation. The…

Solar and Stellar Astrophysics · Physics 2015-06-22 A. P. Boss , S. A. Keiser

We investigate numerically the combined effects of supersonic turbulence, strong magnetic fields and ambipolar diffusion on cloud evolution leading to star formation. We find that, in clouds that are initially magnetically subcritical,…

Astrophysics · Physics 2009-11-10 Zhi-Yun Li , Fumitaka Nakamura

The formation of stars shapes the structure and evolution of entire galaxies. The rate and efficiency of this process are affected substantially by the density structure of the individual molecular clouds in which stars form. The most…

Astrophysics of Galaxies · Physics 2015-06-19 Jouni Kainulainen , Christoph Federrath , Thomas Henning

We present an analysis of the relationship between the orientation of magnetic fields and filaments that form in 3D magnetohydrodynamic simulations of cluster-forming, turbulent molecular cloud clumps. We examine simulated cloud clumps with…

Astrophysics of Galaxies · Physics 2016-12-21 Mikhail Klassen , Ralph E. Pudritz , Helen Kirk

We analyze a suite of thin sheet magnetohydrodynamical simulations based on the formulation of Basu, Ciolek, Dapp & Wurster. These simulations allow us to examine the observational consequences to a star-forming region of varying the input…

Solar and Stellar Astrophysics · Physics 2009-07-22 Helen Kirk , Doug Johnstone , Shantanu Basu

(Abridged) We derive an analytical formula which provides estimates on multiscale gravitational energy distribution using the observed surface density PDF. Our analytical formalism also enables one to convert the observed column density PDF…

Solar and Stellar Astrophysics · Physics 2016-07-07 Guang-Xing Li , Andreas Burkert

We formulate the problem of the formation of magnetically supercritical cores in magnetically subcritical parent molecular clouds, and the subsequent collapse of the cores to high densities, past the detachment of ions from magnetic field…

Astrophysics · Physics 2011-02-11 Konstantinos Tassis , Telemachos Ch. Mouschovias

{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