A study of the kinematic dynamo equation with time-dependent coefficients

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169105· OSTI ID:6334339

Ko, Chungming ^[1]

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1. Chicago Univ., IL (USA)

During an active star formation epoch the interstellar medium of a galaxy is in a hyperactive state, and the average turbulent velocity is higher than in the long periods between star formation epochs. The galactic magnetic field generated by dynamo action depends strongly on the turbulent velocity, so that generation of magnetic field should vary with star formation activity. This paper is a preliminary study of the kinematic dynamo equation with time-dependent coefficients simulating the time dependence of the star formation activities. Ko and Parker argued in a simple model that the thickness of the dynamo region is the most sensitive dynamo parameter. The present work shows that the effect of inflating the galactic disk suddenly is to transform a stationary magnetic field into a growing field while keeping the profile more or less intact. Plane wave solutions for a dynamo with power-law time-dependent parameters show that the field may decay first and then grow, and vice versa, which is quite different from a constant parameter dynamo. 10 refs.

• OSTI ID: 6334339
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 360; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EQUATIONS
FLUID MECHANICS
GALAXIES
HYDRODYNAMICS
INTERSTELLAR MAGNETIC FIELDS
INTERSTELLAR SPACE
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
SPACE
STAR EVOLUTION
TIME DEPENDENCE
TURBULENCE