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We present results from an extensive set of simulations of gravitational fragmentation in the presence of magnetic fields and ambipolar diffusion. The average fragmentation spacing in the nonlinear phase of evolution is in excellent…

Astrophysics · Physics 2008-12-18 Shantanu Basu , Glenn E. Ciolek , James Wurster

Stars form in supersonic turbulent molecular clouds that are self-gravitating. We present an analytic determination of the star formation rate (SFR) in a gravoturbulent medium based on the density probability distribution function of…

Astrophysics of Galaxies · Physics 2018-08-22 Blakesley Burkhart

We discuss the lifetimes and evolution of clumps and cores formed as turbulent density fluctuations in nearly isothermal molecular clouds. In the non-magnetic case, clumps are unlikely to reach a hydrostatic state, and instead are expected…

Multiphase outflows, revealed by multi-wavelength observations, are crucial in redistributing gas and metals within and around galaxies. These outflows are often modelled theoretically using wind tunnel simulations of a cold ($\sim 10^4$ K)…

Astrophysics of Galaxies · Physics 2025-12-10 Alankar Dutta , Prateek Sharma , Max Gronke

We explore the amplification of magnetic fields in the high-redshift Universe. For this purpose, we perform high-resolution cosmological simulations following the formation of primordial halos with \sim10^7 M_solar, revealing the presence…

Via amplification by turbulent dynamo, magnetic fields can be potentially important for the formation of the first stars. To examine the dynamo behavior during the gravitational collapse of primordial gas, we extend the theory of nonlinear…

Solar and Stellar Astrophysics · Physics 2020-08-26 Siyao Xu , Alex Lazarian

The evolution of a large-scale poloidal magnetic field in an accretion disc is an important problem because it determines the launching of winds and the feasibility of the magnetorotational instability to generate turbulence or channel…

Earth and Planetary Astrophysics · Physics 2019-06-19 Philip K. C. Leung , Gordon I. Ogilvie

We calculate and analyze the longevity of magnetohydrodynamic (MHD) wave modes that occur in the plane of a magnetic thin sheet. Initial turbulent conditions applied to a magnetically subcritical cloud are shown to lead to relatively rapid…

Astrophysics of Galaxies · Physics 2013-08-19 Shantanu Basu , Wolf B. Dapp

We investigate the properties of highly compressible turbulence, the compressibility arising from a small effective polytropic exponent $\gamma_e$ due to cooling. In the limit of small $\gamma_e$, the density jump at shocks is shown to be…

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

Recent numerical studies suggest that magnetic fields play an important role in primordial star formation in the early universe. However, the detailed evolution of the magnetic field in the collapse phase still has uncertainties because of…

Astrophysics of Galaxies · Physics 2024-02-27 Sho Higashi , Hajime Susa , Christoph Federrath , Gen Chiaki

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

Through the magnetic braking and the launching of protostellar outflows, magnetic fields play a major role in the regulation of angular momentum in star formation, which directly impacts the formation and evolution of protoplanetary disks…

Solar and Stellar Astrophysics · Physics 2020-09-04 Pierre Marchand , Kengo Tomida , Kei Tanaka , Benoît Commerçon , Gilles Chabrier

We study effect of magnetic field on massive dense core formation in colliding unequal molecular clouds by performing magnetohydrodynamic simulations with sub-parsec resolution (0.015 pc) that can resolve the molecular cores. Initial clouds…

Astrophysics of Galaxies · Physics 2020-07-23 Nirmit Sakre , Asao Habe , Alex R. Pettitt , Takashi Okamoto

We discuss evolution of the magnetic flux density and angular velocity in a molecular cloud core, on the basis of three-dimensional numerical simulations, in which a rotating magnetized cloud fragments and collapses to form a very dense…

Astrophysics · Physics 2009-11-13 Masahiro N Machida , Tomoaki Matsumoto , Kohji Tomisaka , Tomoyuki Hanawa

The transport of angular momentum by magnetic fields is a crucial physical process in formation and evolution of stars and disks. Because the ionization degree in star forming clouds is extremely low, non-ideal magnetohydrodynamic (MHD)…

Solar and Stellar Astrophysics · Physics 2015-06-23 Kengo Tomida , Satoshi Okuzumi , Masahiro N. Machida

The effect of magnetic field diffusion on the stability of accretion disks is a problem that has attracted considerable interest of late. In particular, the Hall effect has the potential to bring about remarkable changes in the dynamical…

Earth and Planetary Astrophysics · Physics 2017-03-29 Gopakumar Mohandas , Martin E. Pessah

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

This paper presents the results of the analysis of 3D simulations of solar magneto-convection that include the joint action of the ambipolar diffusion and the Hall effect. Three simulation-runs are compared: one including both ambipolar…

Solar and Stellar Astrophysics · Physics 2021-01-20 E. Khomenko , M. Collados , N. Vitas , P. A. Gonzalez-Morales

The Zeeman effect and dust grain alignment are two major methods for probing magnetic fields (B-fields) in molecular clouds, largely motivated by the study of star formation, as the B-field may regulate gravitational contraction and channel…

Astrophysics of Galaxies · Physics 2021-06-16 Hua-bai Li

The lower solar atmosphere consists of partially ionized turbulent plasmas harbouring velocity field, magnetic field and current density fluctuations. The correlations amongst these small scale fluctuations give rise to large scale flows…

Solar and Stellar Astrophysics · Physics 2009-04-23 V. Krishan , S. Masuda
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