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The magneto-rotational instability is presently the most promising source of turbulent transport in accretion disks. However, some important issues still need to be addressed to quantify the role of MRI in disks; in particular no systematic…

Astrophysics · Physics 2009-06-23 G. Lesur , P-Y. Longaretti

The magnetorotational instability (MRI) has been suggested to have an important role on the dynamics of accretion disks. We investigate MRI as an alternative way for guiding the plasma from the disk to the funnel flow at the…

High Energy Astrophysical Phenomena · Physics 2012-10-08 S. Dogan , E. R. Pekunlu

We have investigated evolution of magneto-rotational instability (MRI) in protoplanetary disks that have radially non-uniform magnetic field such that stable and unstable regions coexist initially, and found that a zone in which the disk…

Astrophysics · Physics 2011-02-11 M. T. Kato , K. Nakamura , R. Tandokoro , M. Fujimoto , S. Ida

We use smoothed particle hydrodynamics simulations of massive protostellar discs to investigate the predicted broadening of molecular lines from discs in which self-gravity is the dominant source of angular momentum transport. The…

Solar and Stellar Astrophysics · Physics 2015-06-11 Duncan H. Forgan , Philip J. Armitage , Jacob B. Simon

The magnetorotational instability (MRI) is the most promising mechanism by which angular momentum is efficiently transported outwards in astrophysical discs. However, its application to protoplanetary discs remains problematic. These discs…

Earth and Planetary Astrophysics · Physics 2015-06-16 Matthew W. Kunz , Geoffroy Lesur

Turbulence in the protoplanetary disks induces collisions between dust grains, and thus facilitates grain growth. We investigate the two fundamental assumptions of the turbulence in obtaining grain collisional velocities -- the kinetic…

Solar and Stellar Astrophysics · Physics 2020-03-25 Munan Gong , Alexei V. Ivlev , Bo Zhao , Paola Caselli

Detailed calculations of the physical structure of accretion disk boundary layers, and thus their inferred observational properties, rely on the assumption that angular momentum transport is opposite to the radial angular frequency gradient…

High Energy Astrophysical Phenomena · Physics 2012-05-25 Martin E. Pessah , Chi-kwan Chan

(abridged) Context: Turbulent diffusion of large-scale flows and magnetic fields play major roles in many astrophysical systems. Aims: Our goal is to compute turbulent viscosity and magnetic diffusivity, relevant for diffusing large-scale…

Solar and Stellar Astrophysics · Physics 2020-04-29 Petri J. Käpylä , Matthias Rheinhardt , Axel Brandenburg , Maarit J. Käpylä

The theory of jet emitting disks (JEDs) provides a mathematical framework for a self-consistent treatment of steady-state accretion and ejection. A large-scale vertical magnetic field threads the accretion disk where magnetic turbulence…

High Energy Astrophysical Phenomena · Physics 2024-12-11 N. Zimniak , J. Ferreira , J. Jacquemin-Ide

The physical modeling of the accretion disk boundary layer, the region where the disk meets the surface of the accreting star, usually relies on the assumption that angular momentum transport is opposite to the radial angular frequency…

High Energy Astrophysical Phenomena · Physics 2012-11-28 Chi-kwan Chan , Martin E. Pessah

The most efficient energy sources known in the Universe are accretion disks. Those around black holes convert 5 -- 40 per cent of rest-mass energy to radiation. Like water circling a drain, inflowing mass must lose angular momentum,…

Astrophysics · Physics 2009-11-11 Hantao Ji , Michael J. Burin , Ethan Schartman , Jeremy Goodman

Angular momentum transport in accretion disk has been the focus of intense research in theoretical astrophysics for many decades. In the past twenty years, MHD turbulence driven by the magnetorotational instability has emerged as an…

Solar and Stellar Astrophysics · Physics 2015-06-15 Sebastien Fromang

Astrophysical disks are likely embedded in an ambient vertical magnetic field. This ambient field is known to drive magneto-rotational turbulence in the disk bulk but is also responsible for the launching of magnetized outflows at the…

High Energy Astrophysical Phenomena · Physics 2021-03-31 J. Jacquemin-Ide , G. Lesur , J. Ferreira

This paper reports on 3D numerical simulations of dynamics and thermodynamics in the diffuse ISM. Our models are local, account for sheared galactic rotation, magnetic fields, and realistic cooling, and resolve scales ~1-200 pc. This…

Astrophysics · Physics 2009-11-11 Robert A. Piontek , Eve C. Ostriker

The redistribution of angular momentum is a long standing problem in our understanding of protoplanetary disk (PPD) evolution. The magnetorotational instability (MRI) is considered a likely mechanism. We present the results of a study…

Solar and Stellar Astrophysics · Physics 2016-12-07 Donna Rodgers-Lee , Tom P. Ray , Turlough P. Downes

Cosmic ray (CR) transport and acceleration is determined by the properties of magnetic turbulence. Recent advances in MHD turbulence call for revisions in the paradigm of cosmic ray transport. We use the models of magnetohydrodynamic…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Huirong Yan

We measure the turbulent resistivity in the nonlinear regime of the MRI, and evaluate the turbulent magnetic Prandtl number. We perform a set of numerical simulations with the Eulerian finite volume codes Athena and Ramses in the framework…

Solar and Stellar Astrophysics · Physics 2015-05-13 Sebastien Fromang , James M. Stone

The standard magnetorotational instability (SMRI) is a promising mechanism for turbulence and rapid accretion in astrophysical disks. It is a magnetohydrodynamic (MHD) instability that destabilizes otherwise hydrodynamically stable disk…

Accretion disc turbulence is investigated in the framework of the shearing box approximation. The turbulence is either driven by the magneto-rotational instability or, in the non-magnetic case, by an explicit and artificial forcing term in…

Astrophysics · Physics 2008-11-26 Axel Brandenburg

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on…

Earth and Planetary Astrophysics · Physics 2015-06-15 Russell Landry , Sarah E. Dodson-Robinson , Neal J. Turner , Greg Abram