Related papers: Evolution of a magnetic field in a differentially …
We study the time evolution of non-axisymmetric linear perturbations of a rotating magnetised neutron star, whose magnetic field is multipolar and purely poloidal. The background stellar configurations are generated self-consistently,…
We construct barotropic stellar equilibria, containing magnetic fields with both poloidal and toroidal field components. We extend earlier results by exploring the effect of different magnetic field and current distributions. Our results…
We investigate the instability of purely poloidal magnetic fields in nonrotating neutron stars by means of three-dimensional general-relativistic magnetohydrodynamics simulations, extending the work presented in Ciolfi et al. (2011). Our…
Current models of magnetars require extremely strong magnetic fields to explain their observed quiescent and bursting emission, implying that the field strength within the star's outer crust is orders of magnitude larger than the dipole…
The MHD instabilities can generate complex field topologies even if the initial field configuration is a very simple one. We consider the stability properties of magnetic configurations containing a toroidal and an axial field. In this…
As another step towards understanding the long-term evolution of the magnetic field in neutron stars, we provide the first simulations of ambipolar diffusion in a spherical star. Restricting ourselves to axial symmetry, we consider a…
Magnetic perturbations to the frequencies of low degree, high radial order, axisymmetric pulsations in stellar models permeated by large scale magnetic fields are presented. Magnetic fields with dipolar, quadrupolar and a superposition of…
We perform numerical simulations of magneto-rotational instability in a local patch of accretion disk in which radiation pressure exceeds gas pressure. Such conditions may occur in the central regions of disks surrounding compact objects in…
It is well-known that the cores of massive stars sustain a stellar dynamo with a complex magnetic field configuration. However, the same cannot be said for the field's strength and geometry at the convective-radiative boundary, which are…
Magnetic fields in upper main-sequence stars, white dwarfs, and neutron stars are known to persist for timescales comparable to their lifetimes. From a theoretical perspective this is problematic, as it can be shown that simple magnetic…
While magnetic fields have long been considered to be important for the evolution of magnetic non-degenerate stars and compact stars, it has become clear in recent years that actually all of the stars are deeply affected. This is…
(Abridged) We develop a theoretical framework to construct axisymmetric magnetic equilibria in stars, consisting of both poloidal and toroidal magnetic field components. In a stationary axisymmetric configuration, the poloidal current is a…
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…
We explore magnetic field configurations that lead to the formation of magnetic spots on the surface of neutron stars, and to the displacement of the magnetic dipole axis. We find that a toroidally dominated magnetic field is essential for…
During the last decade it has become evident that the magnetorotational instability is at the heart of the enhanced angular momentum transport in weakly magnetized accretion disks around neutron stars and black holes. In this paper, we…
Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10% of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the…
Stability properties of magnetic-field configurations containing the toroidal and axial field are considered. The stability is treated by making use of linear analysis. It is shown that the conditions required for the onset of instability…
In stably stratified stars, numerical magneto-hydrodynamics simulations have shown that arbitrary initial magnetic fields evolve into stable equilibrium configurations, usually containing nearly axisymmetric, linked poloidal and toroidal…
Observations of magnetic A, B and O stars show that the poloidal magnetic flux per unit mass has an upper bound of 10^-6.5 G cm^2/g. A similar upper bound is found for magnetic white dwarfs even though the highest magnetic field strengths…
We perform three-dimensional numerical simulations of stellar winds of early-M dwarf stars. Our simulations incorporate observationally reconstructed large-scale surface magnetic maps, suggesting that the complexity of the magnetic field…