Observations of the interplanetary sector structure up to heliographic latitudes of 16/sup 0/: Pioneer 11

Journal Article · Wed Feb 01 04:00:00 EST 1978 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA083iA02p00717· OSTI ID:5076926

Smith, E J; Tsurutani, B T; Rosenberg, R L

A study of the interplanetary sector structure at heliographic latitudes up to 16/sup 0/N is reported. The study is based on magnetic field measurements made on board Pioneer 11 as the spacecraft traveled along the post-Jupiter-encounter trajectory. Preliminary measurements are used to determine the dominant polarity of the interplanetary magnetic field during 43 successive solar rotations including Pioneer's ascent to its maximum latitude and motion inward from 5 to 3.7 AU. As the latitude of Pioneer increased, the dominant polarity became continually more positive, corresponding to an outward-directed solar interplanetary field. When the spacecraft reached the highest latitude, the usual sector structure had essentially disappeared. A histogram of the field longitude angle, based on data acquired during 1 month at 16/sup 0/ latitude, shows an almost total absence of inward-directed fields. A comparison with interplanetary field polarities in the ecliptic, as inferred from geomagnetic field variations, rules out the possibility that a time variation rather than a latitude dependence is responsible. The Pioneer 11 observations imply that the boundary between adjacent sectors corresponds physically to a current sheet surrounding the sun and lying near parallel to the solar equatorial plane. Above this current sheet, in the northern hemisphere, the field polarity at this phase of the solar cycle is outward, and below the current sheet, in the southern hemisphere, it is inward. The Pioneer observations confirm earlier theoretical suggestions regarding the existence and equatorial orientation of this current sheet. The properties of the current sheet and some major implications and questions associated with it are discussed. It is shown that the radial component of the sheet current is compensated by the distributed currents in the northern and southern hemispheres associated with the spiraled interplanetary field.

• Research Organization: Jet Propulsion Laboratory, Pasadena, California 91103
• OSTI ID: 5076926
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 83:A2; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GEOGRAPHICAL VARIATIONS
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
LATITUDE EFFECT
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
PIONEER SPACE PROBES
PLASMA SHEET
SPACE
SPACE VEHICLES
STARS
SUN
VARIATIONS