Magnetic vortex tubes, jets and nonthermal sources.
Abstract
The generation and dissipation of magnetic fields are discussed. Due to induction the time scale for both processes will be less than the Hubble age only if the field has scale length <1013cm. A hierarchy of vortices is postulated in order to reconcile this scale and the large scale of fields observed in radio jets. The specific viscous forces on electrons and ions in a differentially rotating plasma generate a current whose magnetic field is proportional to vorticity, at least whilst the field is weak enough for gyroradius to exceed mean free path for electrons. For an array of vortices of scale 1013cm fields of 4×10-5G are predicted. Energy in large scale differential rotation is transferred through the hierarchy to small scale vorticity and thence into the magnetic field. During collapse of a spherical rotating gas cloud toward disc geometry, a vortex can form along the rotation axis, being maintained by pressure driving equatorial inflow and bipolar outflow of gas. Stellar bipolar nebulae and jet-lobe radio structures are examples.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1985
- Bibcode:
- 1985A&A...144..298B
- Keywords:
-
- Extragalactic Radio Sources;
- Interstellar Magnetic Fields;
- Magnetohydrodynamics;
- Nonthermal Radiation;
- Plasma Jets;
- Synchrotron Radiation;
- Astronomical Models;
- Cosmic Gases;
- Electron Acceleration;
- Magnetic Field Configurations;
- Magnetic Flux;
- Plasma Pinch;
- Relativistic Electron Beams;
- Rotating Plasmas;
- Stellar Magnetic Fields;
- Vortices;
- Astrophysics