Ulysses observations of a {open_quotes}density hole{close_quotes} in the high-speed solar wind

Journal Article · Sun Feb 01 04:00:00 EST 1998 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/97JA02142· OSTI ID:610747

Riley, P; Gosling, J T; McComas, D J ^[1]; Forsyth, R J ^[2]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
2. The Blackett Laboratory, Imperial College, London, England (United Kingdom)

Ulysses observations at mid and high heliographic latitudes have revealed a solar wind devoid of the large variations in density, temperature, and speed that are commonly observed at low latitudes. One event, however, observed on May 1, 1996, while Ulysses was located at {approximately}3.7AU and 38.5{degree}, stands out in the plasma data set. The structure, which is unique in the Ulysses high-latitude data set, is seen as a drop in proton density of almost an order of magnitude and a comparable rise in proton temperature. The event lasts {approximately}3(1)/(2) hours giving the structure a size of {approximately}9.6{times}10{sup 6}km (0.06 AU) along the spacecraft trajectory. Minimum variance analysis of this interval indicates that the angle between the average magnetic field direction and the minimum variance direction is {approximately}92{degree}, suggesting that the {open_quotes}density hole{close_quotes} may be approximated by a series of planar slabs separated by several tangential discontinuities. We discuss several possible explanations for the origin of this structure, but ultimately the origin of the density hole remains unknown. {copyright} 1998 American Geophysical Union

• OSTI ID: 610747
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A2 Vol. 103; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
PLASMA DENSITY
PROTON DENSITY
PROTON TEMPERATURE
SOLAR CORONA
SOLAR WIND
SPACE VEHICLES