Related papers: Galactic and Accretion Disk Dynamos
We present MHD simulations exploring the launching, acceleration and collimation of jets and disk winds. The evolution of the disk structure is consistently taken into account. Extending our earlier studies, we now consider the…
Radio continuum and polarization observations of several nearby galaxies allowed to determine their vertical scaleheights, magnetic field strengths and large-scale magnetic field patterns. They all show a similar large-scale magnetic field…
The dynamics of a galactic disk in a non-axisymmetric (triaxial) dark halo is studied in detail using high-resolution, numerical, hydrodynamical models. A long-lived, two-armed spiral pattern is generated for a wide range of parameters. The…
The spherical gravitational collapse and virialization of arbitrary density fluctuations in an expanding universe is studied. In the context of the standard cosmological model and the peak $ansatz$, disk galaxies are supposed to be the…
We present results concerning the internal structure and kinematics of disk galaxies formed in cosmologically motivated simulations. The calculations include dark matter, gas dynamics, radiative cooling, star formation, supernova feedback…
We discuss asymptotic solutions of the kinematic $\alpha\omega$-dynamo in a thin disc (slab). Focusing upon the strong dynamo regime, in which the dynamo number $D$ satisfies $|D|\gg1$, we resolve uncertainties in the earlier treatments and…
The stellar metallicity gradients of disc galaxies provide information on the disc assembly, star formation processes and chemical evolution. They also might store information on dynamical processes which could affect the distribution of…
The role of gravitational instability-driven turbulence in determining the structure and evolution of disk galaxies, and the extent to which gravity rather than feedback can explain galaxy properties, remains an open question. To address…
The generation of solar non-axisymmetric magnetic fields is studied based on a linear alpha2-Omega dynamo model in a rotating spherical frame. The model consists of a solar-like differential rotation, a magnetic diffusivity varied with…
Aims. Galaxy mass models based on simple and analytical functions for the density and potential pairs have been widely proposed in the literature. Disk models constrained by kinematic data alone give information on the global disk structure…
We study the self-consistent, linear response of a galactic disc to non-axisymmetric perturbations in the vertical direction as due to a tidal encounter, and show that the density distribution near the disc mid-plane has a strong impact on…
Correlations between stellar kinematics and chemical abundances are fossil evidence for evolutionary connections between Galactic structural components. Extensive stellar surveys show that the only tolerably clear distinction between…
Magnetic field generation on scales large compared with the scale of the turbulent eddies is known to be possible via the so-called $\alpha$ effect when the turbulence is helical and if the domain is large enough for the $\alpha$ effect to…
The Sun and other cool stars harbouring outer convection zones manifest magnetic activity in their atmospheres. The connection between this activity and the properties of a deep-seated dynamo generating the magnetic flux is not well…
A fully three-dimensional computation of induction processes in a disk is performed to investigate the evolution of a large-scale magnetic field in gas-rich barred and spiral galaxies in the presence of field diffusion. As input parameters…
The ordered magnetic field observed via polarized synchrotron emission in nearby disc galaxies can be explained by a mean-field dynamo operating in the diffuse interstellar medium (ISM). Additionally, vertical-flux initial conditions are…
The gas-phase velocity dispersions in disk galaxies, which trace turbulence in the interstellar medium, are observed to increase with lookback time. However, the mechanisms that set this rise in turbulence are observationally poorly…
We study the detailed properties of the radial metallicity gradient in the stellar disk of our Galaxy to constrain its chemical and structural evolution. For this purpose we select and analyze $\sim$ 18,500 disk stars taken from two…
Magnetic fields play an important role in astrophysical accretion discs, and in the interstellar and intergalactic medium. They drive jets, suppress fragmentation in star-forming clouds and can have a significant impact on the accretion…
An update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The…