scholarly journals Non-Axisymmetric Magnetic Structure Generation in Planets Sun and Galaxies

1993 ◽  
Vol 157 ◽  
pp. 263-267
Author(s):  
S.V. Starchenko
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Magnetic Fields ◽  
Magnetic Structure ◽  
Thin Shell ◽  
Spiral Galaxies ◽  
Axially Symmetric ◽  
Structure Generation ◽  
Essential Component

The problem of preferential excitation of non-axially symmetric magnetic fields in most of the observed spiral galaxies and in planets as Uranus and Neptune is studied. It is suggested that a dynamo acting in a thin conductive shell is possible in these objects.It is shown that in this thin shell axisymmetric and non-axisymmetric magnetic field modes can be excited with equal efficiency. The preferential excitation of non-axially symmetric magnetic fields is possible, when the gradient of the angular velocity of rotation is comparatively small and has an essential component perpendicular to the shell.

Circularly Polarized Synchrotron Radiation in Dipolar Magnetic Fields with Application to the Planet Jupiter

1969 ◽  
Vol 1 (6) ◽  
pp. 274-276 ◽  
Author(s):  
L. J. Gleeson ◽  
M. P. C. Legg ◽  
K. C. Westfold
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Magnetic Fields ◽  
Linear Polarization ◽  
Thin Shell ◽  
Total Radiation ◽  
Circularly Polarized ◽  
Preliminary Account ◽  
The Magnetic Field

This paper is a preliminary account of the calculation of the circularly polarized synchrotron radiation received from a distribution of electricallycharged particles confined to a thin shell in the magnetic field of a dipole. Calculations of the total radiation and the degree of linear polarization have previously been carried out, and these calculations are duplicated in part.

scholarly journals Galactic Winds and Magnetic Fields from Spiral Galaxies

1990 ◽  
Vol 140 ◽  
pp. 177-181 ◽  
Author(s):  
H.J. Völk ◽  
D. Breitschwerdt ◽  
J.F. McKenzie
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Mass Loss ◽  
Magnetic Structure ◽  
Essential Role ◽  
Spiral Galaxies ◽  
High Energy ◽  
Energy Component ◽  
Galactic Winds ◽  
High Energy Component

Concentrating on our own Galaxy we discuss the dynamics of the outer halo, its magnetic structure and the occurrence of a supersonic mass loss in the form of a Galactic wind. The cosmic rays, as the nonthermal high energy component, de facto not influenced by gravity, play an essential role in the wind dynamics.

scholarly journals The Magnetic Fields of Pulsars

1974 ◽  
Vol 64 ◽  
pp. 187-187
Author(s):  
D. M. Sedrakian
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Magnetic Fields ◽  
Relative Motion ◽  
Kinematic Viscosity ◽  
Charged Particles ◽  
Normal Fluid ◽  
Inertia Effects ◽  
Generation Mechanisms ◽  
Image Position

Two generation mechanisms of magnetic fields in pulsars are considered.If the temperature of a star is more than 108K, the star consists of a normal fluid of neutrons, protons and electrons. Because the angular velocity of pulsars is not constant dω/dt ≠0, inertia effects can occur, and generate magnetic fields through the relative motion of charged particles with different masses. The kinematic viscosity of electrons is 30 times larger than that of protons; hence electrons move with the crust, but the proton-neutron fluid will move relative to the electrons. The magnetic momentum can be calculated by the following formula where Meff = Mp + Mn(Nn/Np), R = radius of the star, σ = conductivity. For typical neutron stars we have dω/dt~ 10-8 s-2, R~106 cm, σ~1029 s-1 and we get a magnetic field of the order of 1010 G.

scholarly journals Dynamo in Astrophysics

1990 ◽  
Vol 140 ◽  
pp. 83-89
Author(s):  
A.A. Ruzmaikin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turbulent Flow ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Clusters Of Galaxies ◽  
Magnetic Structures ◽  
Random Magnetic Field ◽  
Astrophysical Objects

The fast dynamo acting in a turbulent flow explains the origin of magnetic fields in astrophysical objects. Stellar cycles and large-scale magnetic fields in spiral galaxies reflect the behaviour of a mean magnetic field. Intermittent magnetic structures in clusters of galaxies are associated with random magnetic field.

Magnetic Fields and Star Formation for the ANS Sample of Galaxies

1990 ◽  
Vol 140 ◽  
pp. 233-234
Author(s):  
J. Stryczynski
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Magnetic Fields ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Field Data ◽  
Spiral Galaxies ◽  
Magnetic Field Data ◽  
Uv Range

From the literature we collected radio and magnetic field data for the ANS spiral galaxies. We suggest that the groups of objects, as revealed in the UV range, do not differ in magnetic field strength, although statistics of the sample are very poor.

scholarly journals Magnetic Field Strengths of Spiral Galaxies and the Far-Infrared/Radio Correlation

1990 ◽  
Vol 140 ◽  
pp. 241-241
Author(s):  
A. J. Fitt ◽  
P. Alexander
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Distribution ◽  
Detection Rate ◽  
Spiral Galaxies ◽  
Far Infrared ◽  
Magnetic Field Distribution ◽  
Selection Effects ◽  
The Magnetic Field ◽  
Field Strengths

We have calculated equipartition magnetic fields for a complete, optically-selected sample of 165 spiral galaxies. The magnetic field distribution (fig. 1) is type independent, and shows remarkably little spread in values, around 1 decade in B. This is not due to selection effects because of the nature of the sample and the 95 percent detection rate.

scholarly journals Stability of H3O at extreme conditions and implications for the magnetic fields of Uranus and Neptune

2020 ◽  
Vol 117 (11) ◽  
pp. 5638-5643 ◽  
Author(s):  
Peihao Huang ◽  
Hanyu Liu ◽  
Jian Lv ◽  
Quan Li ◽  
Chunhong Long ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Thin Shell ◽  
Underlying Mechanism ◽  
Giant Planets ◽  
Dynamo Model ◽  
Extreme Conditions ◽  
Material Basis ◽  
The Magnetic Field ◽  
Planetary Dynamos

The anomalous nondipolar and nonaxisymmetric magnetic fields of Uranus and Neptune have long challenged conventional views of planetary dynamos. A thin-shell dynamo conjecture captures the observed phenomena but leaves unexplained the fundamental material basis and underlying mechanism. Here we report extensive quantum-mechanical calculations of polymorphism in the hydrogen–oxygen system at the pressures and temperatures of the deep interiors of these ice giant planets (to >600 GPa and 7,000 K). The results reveal the surprising stability of solid and fluid trihydrogen oxide (H3O) at these extreme conditions. Fluid H3O is metallic and calculated to be stable near the cores of Uranus and Neptune. As a convecting fluid, the material could give rise to the magnetic field consistent with the thin-shell dynamo model proposed for these planets. H3O could also be a major component in both solid and superionic forms in other (e.g., nonconvecting) layers. The results thus provide a materials basis for understanding the enigmatic magnetic-field anomalies and other aspects of the interiors of Uranus and Neptune. These findings have direct implications for the internal structure, composition, and dynamos of related exoplanets.

scholarly journals Пылевая плазма в тлеющем разряде в магнитном поле до 3000 G

2018 ◽  
Vol 44 (19) ◽  
pp. 66
Author(s):  
Е.С. Дзлиева ◽  
Л.А. Новиков ◽  
С.И. Павлов ◽  
В.Ю. Карасев
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Glow Discharge ◽  
Magnetic Fields ◽  
Dusty Plasma ◽  
Drag Force ◽  
Applied Magnetic Field ◽  
Magnetic Trap ◽  
Current Channel ◽  
Angular Velocities

AbstractA glow discharge dusty plasma in a magnetic trap in which the current channel narrows is obtained in moderate magnetic fields up to 3000 G. The results of initial experiments are reported. The formation of stable dusty plasma structures rotating at record-high angular velocities up to 15 rad/s is observed. The dependence of the angular velocity on the strength of the applied magnetic field is measured experimentally. We interpret it quantitatively on the basis of the ion drag force.

scholarly journals 3D model of magnetic fields evolution in dwarf irregular galaxies

2010 ◽  
Vol 6 (S274) ◽  
pp. 389-392
Author(s):  
Hubert Siejkowski ◽  
Marian Soida ◽  
Katarzyna Otmianowska-Mazur ◽  
Michał Hanasz ◽  
Dominik J. Bomans
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Gravitational Potential ◽  
Spiral Galaxies ◽  
Cosmic Ray ◽  
Dynamo Model ◽  
Slow Rotation ◽  
Irregular Galaxies ◽  
Dwarf Irregular Galaxies ◽  
The Magnetic Field

AbstractRadio observations show that magnetic fields are present in dwarf irregular galaxies (dIrr) and its strength is comparable to that found in spiral galaxies. Slow rotation, weak shear and shallow gravitational potential are the main features of a typical dIrr galaxy. These conditions of the interstellar medium in a dIrr galaxy seem to unfavourable for amplification of the magnetic field through the dynamo process. Cosmic-ray driven dynamo is one of the galactic dynamo model, which has been successfully tested in case of the spiral galaxies. We investigate this dynamo model in the ISM of a dIrr galaxy. We study its efficiency under the influence of slow rotation, weak shear and shallow gravitational potential. Additionally, the exploding supernovae are parametrised by the frequency of star formation and its modulation, to reproduce bursts and quiescent phases. We found that even slow galactic rotation with a low shearing rate amplifies the magnetic field, and that rapid rotation with a low value of the shear enhances the efficiency of the dynamo. Our simulations have shown that a high amount of magnetic energy leaves the simulation box becoming an efficient source of intergalactic magnetic fields.

scholarly journals 3D numerical simulations of magnetic field evolution in barred galaxies and in spiral galaxies under influence of tidal forces

2010 ◽  
Vol 6 (S274) ◽  
pp. 381-384
Author(s):  
Katarzyna Otmianowska-Mazur ◽  
Katarzyna Kulpa-Dybeł ◽  
Barbara Kulesza-Żydzik ◽  
Hubert Siejkowski ◽  
Grzegorz Kowal
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Cosmic Ray ◽  
Mhd Equations ◽  
Back Reaction ◽  
Barred Galaxies ◽  
Tidal Forces ◽  
Field Evolution

AbstractWe present the results of the three-dimensional, fully non-linear MHD simulations of the large-scale magnetic field evolution in a barred galaxy with the back reaction of magnetic field to gas. We also include the process of the cosmic-ray driven dynamo. In addition, we check what physical processes are responsible for the magnetic field evolution in the tidally influenced spiral galaxies. We solve the MHD equations for the gas and magnetic field in a spiral galaxy with gravitationally prescribed bulge, disk and halo which travels along common orbit with the second body. In order to compare our modeling results with the observations we also construct the maps of high-frequency (Faraday rotation-free) polarized radio emission from the simulated magnetic fields. The model accounts for the effects of projection and limited resolution.We found that the obtained magnetic field configurations are highly similar to the observed maps of the polarized intensity of barred galaxies, because the modeled vectors form coherent structures along the bar and spiral arms. We also found a physical explanation of the problem of inconsistency between the velocity and magnetic fields character present in this type of galaxies. Due to the dynamical influence of the bar, the gas forms spiral waves which go radially outward. Each spiral arm forms the magnetic arm which stays much longer in the disk than the gaseous spiral structure. The modeled total energy of magnetic field and magnetic flux grows exponentially due to the action of the cosmic-ray driven dynamo. We also obtained the polarization maps of tidally influenced spiral galaxies which are similar to observations.

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