Dynamo in Astrophysics
Abstract
The origin of magnetic fields in astrophysical objects is developed theoretically in a discussion of the fast dynamo. Magnetic fields are described as being 'frozen,' but the complexity of turbulent astrophysical flows facilitates the generation of the magnetic field. The role of the mean magnetic field is considered in terms of stellar activity cycles as well as large-scale magnetic structures in spiral galaxies. Specific examples are given for the application of the notion of 'small-scale', intermittent magnetic fields to clusters of galaxies. The geometry of the Galactic dynamo is developed in terms of its mean helicity, as derived from observations of the velocity field. Plasma hydrodynamical motions are shown to preside in the inception of magnetic fields in stars and galaxies, and the dynamo process is theorized to be acting on observed plasmas with high magnetic Reynolds numbers.
- Publication:
-
Galactic and Intergalactic Magnetic Fields
- Pub Date:
- 1990
- Bibcode:
- 1990IAUS..140...83R
- Keywords:
-
- Dynamo Theory;
- Interstellar Magnetic Fields;
- Magnetic Field Configurations;
- Turbulent Flow;
- Magnetic Flux;
- Magnetohydrodynamic Turbulence;
- Magnetohydrodynamics;
- Stellar Activity;
- Astrophysics