Magnetized thermal conduction fronts. [Between hot and cold astrophysical plasma]

Journal Article · Thu May 01 04:00:00 EDT 1986 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/164216· OSTI ID:5228175

Balbus, S A

The evolution of planar thermal conduction fronts in the presence of a dynamically weak, but otherwise self-consistent, magnetic field is considered. The field is assumed to be connected and untangled. In the diffusion limit for the thermal conductivity, these fronts exhibit self-similar behavior, even in the presence of a field. The role of the field is restricted to channeling the heat flux along its lines of force, and it enters into the problem as a dimensionless angle variable. Combing (or opening) of insulating field lines by the evaporative flow is explicitly demonstrated. Unless the field is nearly perpendicular to the front normal in the hot gas, insulating effects are not profound. Self-similarity breaks down if the front becomes saturated, and under certain conditions magnetized saturated conduction fronts cannot propagate: the solution characteristics of the wave equation form caustics. The physical resolution is the advent of two-fluid (nonlocal) heating. Such Coulomb-heated fronts are expected to be relatively rare in typical astrophysical systems. The large-scale effects of a magnetic field on cloud evaporation in the interstellar medium are briefly discussed, and it is suggested that these fields preclude the presence of time-independent evaporative solutions. Thermal interfaces may then continue to evolve until radiative cooling halts their development; large tracts of warm 10,000 K gas may result. 18 references.

• Research Organization: Princeton Univ. Observatory, NJ
• OSTI ID: 5228175
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 304; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
FLUID MECHANICS
HYDRODYNAMICS
INTERSTELLAR SPACE
MAGNETIC FIELD CONFIGURATIONS
MAGNETOHYDRODYNAMICS
MECHANICS
NEBULAE
PHYSICAL PROPERTIES
PLASMA
SELF-CONSISTENT FIELD
SPACE
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES