August 1972 solar-terrestrial events: Observations of interplanetary shocks at 2. 2 A U

Journal Article · Tue Mar 01 04:00:00 EST 1977 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA082i007p01077· OSTI ID:7313241

Smith, E J; Davis, L Jr; Coleman, Jr, P J; Colburn, D S; Dyal, P; Jones, D E

Pioneer 10 magnetic field measurements, supplemented by previously published plasma data, have been used to identify shocks at 2.2 AU associated with the large solar flares of early August 1972. The first three flares, which gave rise to three forward shocks at Pioneer 9 and at Earth, led to only a single forward shock at Pioneer 10. The fourth solar flare also gave rise to a forwaerd shock at Pioneer 10 as well as at Pioneer 9. The general finding that the local velocities of both shocks are approximately equal at 0.8 and 2.2 AU but significantly slower than the average speeds nearer the sun is interpreted as evidence of a major deceleration of the shocks as they propagate outward from the sun that is essentially completed when the shocks reach 0.8 AU, there being little, if any, subsequent deceleration. This conclusion is qualitatively inconsistent with previous inferences of a deceleration of the shocks as they propagate from 0.8 to 2.2 AU. A third, reverse shock is also identified in the Pioneer 10 data which was not seen either at Pioneer 9 or at Earth. The estimated speed of this shock is 530 km/s, and its estimated thickness is approximately-less-than 500 km, which compares well with an anticipated proton inertial length of 500 km.

• Research Organization: Jet Propulsion Laboratory, Pasadena, California 91103
• OSTI ID: 7313241
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 82:7; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
640107 -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
ELEMENTARY PARTICLES
FERMIONS
FORBUSH DECREASE
HADRONS
INTERPLANETARY SPACE
MAGNETIC STORMS
NUCLEONS
PIONEER SPACE PROBES
PROTONS
RADIATIONS
SHOCK WAVES
SOLAR ACTIVITY
SOLAR FLARES
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SPACE
SPACE VEHICLES
STELLAR RADIATION