相关论文: Magnetorotational instability in protoplanetary di…

We perform 3D vertically-stratified local shearing-box ideal MHD simulations of the magnetorotational instability (MRI) that include a net vertical magnetic flux, which is characterized by beta_0 (ratio of gas pressure to magnetic pressure…

Sub-mm observations of protoplanetary disks now approach the acuity needed to measure the turbulent broadening of molecular lines. These measurements constrain disk angular momentum transport, and furnish evidence of the turbulent…

Though usually treated in isolation, the magnetorotational and gravitational instabilities (MRI and GI) may coincide at certain radii and evolutionary stages of protoplanetary discs and active galactic nuclei. Their mutual interactions…

Non-ideal MHD effects have been shown recently as a robust mechanism of averting the magnetic braking "catastrophe" and promoting protostellar disc formation. However, the magnetic diffusivities that determine the efficiency of non-ideal…

Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure…

The early evolution of protostellar, star-forming discs, including their density structure, turbulence, magnetic dynamics, and accretion variability, remains poorly understood. We present high-resolution magnetohydrodynamic simulations,…

We present the results obtained from linear stability analysis and 2.5-dimensional magnetohydrodynamic (MHD) simulations of the magnetorotational instability (MRI), including the effects of cosmic rays (CRs). We took into account of the CR…

(Abridged) In this paper we have used the RIEMANN code for computational astrophysics to study the interaction of a realistic distribution of dust grains with gas in a vertically stratified protostellar accretion disc. The disc was modeled…

Magnetorotational turbulence and magnetically driven disc winds are often considered as separate processes. However, realistic astrophysical discs are expected to be subject to both effects, although possibly at different times and…

The initial magnetic field of previous magnetorotational instability (MRI) simulations has always included a significant system-scale component, even if stochastic. However, it is of conceptual and practical interest to assess whether the…

Protoplanetary discs are made of gas and dust orbiting a young star. They are also the birth place of planetary systems, which motivates a large amount of observational and theoretical research. In these lecture notes, I present a review of…

We examine the excitation of unstable magnetosonic waves in the radiative envelopes of intermediate- and high-mass stars with a magnetic field of ~kG strength. Wind clumping close to the star and microturbulence can often be accounted for…

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…

We investigate the viability of the magnetorotational instability (MRI) in accretion disks around both solar-type stars and very low mass stars. In particular, we determine the disk regions where the MRI can be shut off either by Ohmic…

We identify and study a number of new, rapidly growing instabilities of dust grains in protoplanetary disks, which may be important for planetesimal formation. The study is based on the recognition that dust-gas mixtures are generically…

The strength and structure of the large-scale magnetic field in protoplanetary discs are still unknown, although they could have important consequences for the dynamics and evolution of the disc. Using a mean-field approach in which we…

This paper is the first in a series investigating magnetohydrodynamic instabilities that may contribute to angular-momentum transport and magnetic-field evolution in stellar radiative zones. We focus on shear-driven instabilities,…

We investigate the formation and fragmentation of discs using a suite of three-dimensional smoothed particle radiative magnetohydrodynamics simulations. Our models are initialised as 1M$_\odot$ rotating Bonnor-Ebert spheres that are…

The magnetorotational instability originates from the elastic coupling of fluid elements in orbit around a gravitational well. Since inertial accelerations play a fundamental dynamical role in the process, one may expect substantial…

Stratified disks with strong horizontal magnetic fields are susceptible to magnetic buoyancy instability (MBI). Modifying the magnetic field and gas distributions, this can play an important role in galactic evolution. The MBI and the…