Evolution of interplanetary slow shocks

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA01p00251· OSTI ID:5927563

Whang, Y C ^[1]

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1. Catholic Univ. of America, Washington, DC (United States)

The possible existence of traveling forward slow shocks, their global geometry and their transition to forward fast shocks have been discussed in a recent paper. The decrease in the Alfven speed at increasing heliocentric distance causes the evolution of a forward slow shock into a forward fast shock. During the transition the shock system consists of a slow shock, a fast shock, and a rotational discontinuity. This paper continues to discuss three aspects about the evolution of interplanetary slow shocks. The authors first presents a survey of slow shock solutions in a three-dimensional A,{theta},{beta} parameter space. Here A=U{sub n}/(a cos {theta}) is the shock Alfven number, U{sub n} the normal component of the relative shock speed, a the Alfven speed, {theta} the acute angle between the shock normal and the magnetic field, and {beta} the ratio of the thermal pressure p to the magnetic pressure B{sup 2}/8{pi}. In a region where the plasma {beta} value is on the order of 1 or greater, the jumps in thermodynamic properties across a slow shock are small but the directional changes for the magnetic field and the relative flow velocity are not necessarily small. On the other hand, in the region where the plasma {beta} value is on the order of 0.1 or less, the jumps of all physical properties across a slow shock may vary over a wide range of magnitudes. Next, the authors discuss that at the onset of the transition process an interplanetary slow shock smoothly converts to a system consisting of a slow shock, a very weak rotational discontinuity (an Alfven wave), and a very weak fast shock (a fast MHD wave). The authors also show that during the transition, the amplitude of fluctuations in flow velocity and magnetic fields are large in the turbulent region behind the fast shock.

• OSTI ID: 5927563
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 93:A1; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
ATMOSPHERES
COMPRESSION
DISTANCE
FLUCTUATIONS
FLUID MECHANICS
HELIOSPHERE
HYDRODYNAMICS
HYDROMAGNETIC WAVES
INTERPLANETARY SPACE
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS TRANSFER
MECHANICS
SHOCK WAVES
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR FLARES
SOLAR WIND
SPACE
STELLAR ATMOSPHERES
STELLAR CORONAE
TRAVELLING WAVES
VARIATIONS
VELOCITY