Related papers: Magnetically Controlled Accretion Flows onto Young…
The theory of magnetically accelerated outflows and jets from accretion disks is reviewed at an introductory level, with special attention to problem areas like the launching conditions of the flow at the disk surface, stability of the…
The dust- and gas-rich protoplanetary disks around young stellar systems play a key role in star and planet formation. While considerable progress has recently been made in probing these disks on large scales of a few tens of astronomical…
There are X-ray pulsating sources that are explained by accretion from disks around neutron stars. Such disks deserve a detailed analysis. In particular, the dipole magnetic field of the central star may penetrate the disk, giving rise to…
Young stellar objects are thought to accrete material from their circumstellar disks through their strong stellar magnetospheres. We aim to directly probe the magnetospheric accretion region on a scale of a few 0.01 au in a young stellar…
In the early stages of star formation, boundary layer accretion, where protostars accrete material from disks extending down to their surfaces, plays a crucial role. Understanding how a magneto-rotational-instability (MRI)-active disk…
Accretion disks are one of the key ingredients of the star formation process. They redistribute angular momentum and, in the case of high-mass stars (M > 8Msun), disks would relieve the radiation pressure on the accreting material, in…
We report on the second phase of our study of slightly rotating accretion flows onto black holes. We consider magnetohydrodynamical (MHD) accretion flows with a spherically symmetric density distribution at the outer boundary, but with…
Aims: I report results in numerical simulations of star-disk magnetospheric interaction. A thin accretion disk with corona above a rotating stellar surface is simulated in a parameter study, to find trends in the angular momentum flux. The…
In young circumstellar disks, accretion--the inspiral of disk material onto the central star--is important for both the buildup of stellar masses and the outcome of planet formation. Although the existence of accretion is well documented,…
We present results of axisymmetic magnetohydrodynamic simulations of the interaction of a rapidly-rotating, magnetized star with an accretion disk. The disk is considered to have a finite viscosity and magnetic diffusivity. The main…
We study the time evolution of a large-scale magnetic flux threading an accretion disk. Induction equation of the mean poloidal field is solved under the standard viscous disk model. Magnetic flux evolution is controlled by the two…
Our understanding of the dynamical processes which control the structure and evolution of the interaction region between an accretion disk and the central star is reviewed. If the central star is unmagnetized, this interaction is in the…
We present a self-consistent, bimodal stationary solution for spherically symmetric flows driven by young massive stellar clusters with a central supermassive black hole. We demonstrate that the hydrodynamic regime of the flow depends on…
Stars form in dense cores of magnetized molecular clouds. If the magnetic flux threading the cores is dragged into the stars, the stellar field would be orders of magnitude stronger than observed. This well-known "magnetic flux problem"…
Current theoretical models for the outflows/jets from AGN, X-ray binaries and young stellar objects involve large-scale magnetic fields threading an underlying accretion disk. We suggest that such a disk is subjected to warping instability…
(abridged) AIMS. We investigate the dynamics and stability of post-shock plasma streaming along nonuniform stellar magnetic fields at the impact region of accretion columns. We study how the magnetic field configuration and strength…
The inner region of the accretion disk around a magnetized star is subjected to magnetic torques that induce warping and precession of the disk. These torques arise from interactions between the stellar field and the induced electric…
We study protoplanetary disc evolution assuming that angular momentum transport is driven by gravitational instability at large radii, and magnetohydrodynamic (MHD) turbulence in the hot inner regions. At radii of the order of 1 AU such…
In this paper we examine time-dependent and three-dimensional perturbations of spherical accretion flow onto a neutron star close to its Eddington limit. Our treatment assumes a Schwarzschild geometry for the spacetime outside the neutron…
Describing the large-scale field topology of protoplanetary disks faces significant difficulties and uncertainties. The transport of the large-scale field inside the disk plays an important role in understanding its evolution. We aim to…