相关论文: Mechanisms of Planetary and Stellar Dynamos
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 dynamo effect is the most popular candidate to explain the non-primordial magnetic fields of astrophysical objects. Although many systematic studies of parameters have already been made to determine the different dynamical regimes…
In this paper we first discuss observational evidence of longitudinal concentrations of magnetic activity in the Sun and rapidly rotating late-type stars with outer convective envelopes. Scenarios arising from the idea of rotationally…
Stars play a key role in the evolution of the Universe, as sources of radiation, as dynamical engines, and as chemical factories. Outputs of stellar models are then central to various studies in astrophysics. Stellar physics links…
It is useful to study the space of all cosmological models from a dynamical systems perspective, that is, by formulating the Einstein field equations as a dynamical system using appropriately normalized variables. We will discuss various…
Recent simulations of supernova-driven turbulence within the ISM support the existence of a large-scale dynamo. With a growth time of about two hundred million years, the dynamo is quite fast -- in contradiction to many assertions in the…
This paper explores the connection between dynamical system properties and statistical physics of ensembles of such systems. Simple models are used to give novel phase transitions; particularly for finite N particle systems with many…
We present a dynamo mechanism arising from the presence of barotropically unstable zonal jet currents in a rotating spherical shell. The shear instability of the zonal flow develops in the form of a global Rossby mode, whose azimuthal…
We argue that pitch angles of the azimuthally averaged large-scale or mean magnetic fields in nearby spiral galaxies inferred from observations can tentatively be explained with simple galactic dynamo models. Agreement is not perfect, but…
We study the existence of stationary solutions of the Vlasov-Poisson system with finite radius and finite mass in the stellar dynamics case. So far, the existence of such solutions is known only under the assumption of spherical symmetry.…
We examine the effects of the magnetic field created by the Tayler--Spruit dynamo in differentially rotating stars. Magnetic fields of the order of a few $10^4$ G are present through most of the stellar envelope, with the exception of the…
Context: dynamo action in giant planets and rapidly rotating stars leads to a broad variety of magnetic field geometries including small scale multipolar and large scale dipole-dominated topologies. Previous dynamo models suggest that…
Magnetic fields have been constrained at the surface of several massive and intermediate-mass stars, but their origin and properties in deep stellar radiative interiors are still debated, despite recent detections in the core of some red…
Magnetic buoyancy (MBI) and Parker instabilities are strong, generic instabilities expected to occur in most astrophysical systems with sufficiently strong magnetic fields. In galactic and accretion discs, large-scale magnetic fields are…
Magnetic fields have been included in cosmological simulations of galaxy formation only recently, due to advances in numerical techniques and a better understanding of the galaxy formation physics. In this paper, we develop a new subgrid…
Understanding the stability of the magnetic field in radiation zones is of crucial importance for various processes in stellar interior like mixing, circulation and angular momentum transport. The stability properties of a star containing a…
Several lines of evidence suggest that protogalactic and galactic environments manage to grow magnetic field very rapidly. This makes the theoretical problem of achieving rapid growth of magnetic fields in such environments difficult.…
Supernovae are the dominant energy source for driving turbulence within the interstellar plasma. Until recently, their effects on magnetic field amplification in disk galaxies remained a matter of speculation. By means of self-consistent…
Late-type stars rotate differentially owing to anisotropic turbulence in their outer convection zones. The rotation is called solar-like (SL) when the equator rotates fastest and anti-solar (AS) otherwise. Hydrodynamic simulations show a…
The evolution of large-scale magnetic fields in disk galaxies is investigated numerically. The gasdynamical simulations in a disk perturbed by spiral or bar potential are incorporated into the kinematic calculations of induction equations…