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in subjects: "Solar Wind"

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Giotto observations of the bow shock at Comet Halley

Preliminary results from the JPA instrument on Giotto indicate that Comet Halley, even on the flanks, has a bow shock which moves backwards and forwards over the spacecraft. To understand the structure properly will require more detailed investigation of the relationships between three particle populations, cometary ions, solar wind ions and electrons.

Date: January 1, 1986

Creator: Formisano, V.; Amata, E.; Wilken, B.; Jockers, K.; Johnstone, A.; Coates, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Simulation experiments and solar wind sputtering

In order to isolate the role played by solar wind sputtering from other lunar surface phenomena a number of simulation experiments were performed, including isotope abundance measurements of Ca sputtered from terrestrial fluorite and plagioclase by 50-keV and 130-keV /sup 14/N beams, measurement of the energy distribution of U atoms sputtered with 80-keV /sup 40/Ar, and measurement of the fraction of sputtered U atoms which stick on the surfaces used to collect these atoms. 10 references. (JFP)

Date: January 1, 1978

Creator: Griffith, J. E.; Papanastassiou, D. A.; Russell, W. A.; Tombrello, T. A. & Weller, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Counterstreaming solar wind halo electron events on open field lines

Counterstreaming solar wind halo electron events have been identified as a common 1 AU signature of coronal mass ejection events, and have generally been interpreted as indicative of closed magnetic field topologies, i.e., magnetic loops or flux ropes rooted at both ends in the Sun, or detached plasmoids. In this paper we examine the possibility that these events may instead occur preferentially on open field lines, and that counterstreaming results from reflection or injection behind interplan… more

Date: January 1, 1991

Creator: Gosling, J.T.; McComas, D.J. & Phillips, J.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The extension of solar magnetic fields into interplanetary space

The flow of coronal plasma into interplanetary space results in outward transport of the solar magnetic field. The prevailing open'' interplanetary magnetic field is rooted in the corona and wraps up into a spiral due to the rotation of the Sun. This simple configuration, however, is disrupted by magnetically distinct coronal mass ejections (CMEs) which erupt from the solar corona into interplanetary space. Observations of CMEs at 1 AU reveal electron signatures indicating a closed magnetic top… more

Date: January 1, 1991

Creator: McComas, D.J. & Phillips, J.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Quantitative analysis of bidirectional electron fluxes within coronal mass ejections at 1 AU

The solar wind electron heat flux is carried primarily by suprathermal halo'' electrons beamed antisunward along the interplanetary magnetic field (IMF), indicating magnetic connection to the Sun only in one direction. However, electron observations at 1 AU show that counterstreaming halo beams, suggesting closed magnetic structures, prevail within coronal mass ejections (CMEs). These structures might be magnetic tongues'', tied to the Sun at both ends, magnetically detached plasmoids, or compl… more

Date: January 1, 1991

Creator: Phillips, J.L.; Gosling, J.T.; McComas, D.J.; Bame, S.J. & Feldman, W.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comet tail formation: Giotto observations

The process of mass loading of the solar wind by cometary ions, which forms comet tails, has been observed throughout the coma of comet Halley. Three distinct regimes were found where the nature of the energy and momentum coupling between solar wind and cometary ions is different. Outside the bow shock, where there is little angular scattering of the freshly ionized particles, the coupling is described by the simple pickup trajectory and the energy is controlled by the angle between the flow an… more

Date: January 1, 1986

Creator: Wilken, B.; Jockers, K.; Johnstone, A.; Coates, A.; Heath, J.; Formisano, V. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solar wind flows associated with hot heavy ions

Solar wind heavy ion spectra measured with the Vela instrumentation have been studied with the goal of determining the solar origins of various solar wind structures which contain anomalously high ionization states. Since the ionization states freeze-in close to the sun they are good indicators of the plasma conditions in the low and intermediate corona. Heavy ion spectra from three different periods throughout the solar cycle have been analyzed. These data are consistent with freezing-in tempe… more

Date: May 1, 1980

Creator: Fenimore, E.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Plasma sheet behavior during substorms

Auroral or magnetic substorms are periods of enhanced auroral and geomagnetic activity lasting one to a few hours that signify increased dissipation of energy from the magnetosphere to the earth. Data acquired during the past decade from satellites in the near-earth sector of the magnetotail have suggested that during a substorm part of the plasma sheet is severed from earth by magnetic reconnection, forming a plasmoid, i.e., a body of plasma and closed magnetic loops, that flows out of the tai… more

Date: January 1, 1983

Creator: Hones, E.W. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Plasma observations at Comet Halley

In the plasma flow round Comet Halley two unexpected structural features were observed in addition to the anticipated bow shock and contact discontinuity. These features, observed between the structure identified as bow shock and the contact discontinuity are described. 8 refs., 2 figs.

Date: January 1, 1986

Creator: Johnstone, A.D.; Coates, A.; Heath, J.; Formisano, V.; Amata, E.; Wilken, B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Composition and energetics of solar flare particle events measured by satellites, 1989--1991

The Synchronous Orbit Particle Analyzer (SOPA), on board the satellite 1989-046 and others, has detected ions from carbon through nickel at energies from 2 to 50 MeV in the great solar energetic particle events of the current solar cycle. Energetic protons from the same events have been detected by the Charged Particle Analyzer (CPA) on board the satellite 1984-129 and others. We present here a collection of data from these various instruments that includes events of 1989, 1990, and 1991. We de… more

Date: January 1, 1991

Creator: Gisler, G.R.; Belian, R.D.; Cayton, T.E. & Reeves, G.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observations of flux transfer events: Are FTEs flux ropes, islands, or surface waves

Flux transfer events (FTEs) are widely regarded as a signature of transient magnetic reconnection between the solar wind and magnetospheric plasmas. However, there is disagreement on what form this reconnection takes: Are FTEs tearing islands, or time-varying single x-line reconnection We reexamine the evidence that first led to the suggestion that FTEs are related to a non-time-stationary reconnection process. In particular we discuss how the combination of field and plasma variations suggest … more

Date: January 1, 1989

Creator: Elphic, R. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Linear filters as a method of real-time prediction of geomagnetic activity

Important factors controlling geomagnetic activity include the solar wind velocity, the strength of the interplanetary magnetic field (IMF), and the field orientation. Because these quantities change so much in transit through the solar wind, real-time monitoring immediately upstream of the earth provides the best input for any technique of real-time prediction. One such technique is linear prediction filtering which utilizes past histories of the input and output of a linear system to create a… more

Date: January 1, 1985

Creator: McPherron, R.L.; Baker, D.N. & Bargatze, L.F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The relation of solar wind structure to hydromagnetic discontinuities

High resolution ISEE-3 data have been used to examine the relative abundances of tangential (TD) vs rotational (RD) discontinuities in different types of solar wind flow. Three types of flow were examined; flow from coronal holes, sector boundary flow and transient flow. It has been found that coronal hole flow has substantially more discontinuities and a greater ratio of RD's to TD's than do the other types of flow. Discontinuities are least frequent in transient flows characterized by bidirec… more

Date: January 1, 1987

Creator: Alexander, C. J.; Neugebauer, M.; Smith, E. J. & Bame, S. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

In situ observations of coronal mass ejections in interplanetary space

Coronal mass ejections, CMEs, in the solar wind at 1 AU generally have distinct plasma and field signatures by which they can be distinguished from the ordinary solar wind. These include one or more of the following: helium abundance enhancements, ion and electron temperature depressions, unusual ionization states, strong magnetic fields, low plasma beta, low magnetic field variance, coherent field rotations, counterstreaming (along the field) energetic protons, and counterstreaming supratherma… more

Date: January 1, 1991

Creator: Gosling, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Real-time ISEE data system

Prediction of geomagnetic substorms and storms would be of great scientific and commercial interest. A real-time ISEE data system directed toward this purpose is discussed in detail. Such a system may allow up to 60+ minutes advance warning of magnetospheric substorms and up to 30 minute warnings of geomagnetic storms (and other disturbances) induced by high-speed streams and solar flares. The proposed system utilizes existing capabilities of several agencies (NASA, NOAA, USAF), and thereby min… more

Date: January 1, 1979

Creator: Tsurutani, B.T. & Baker, D.N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Numerical simulations on the magnetopause current layer

One-dimensional particle simulations are carried out in order to study the current layer between a plasma and magnetic field such as seen at the magnetopause boundary layer. When a subsonic solar wind plasma flow impinges upon a vacuum dipole magnetic field, the width of the current layer is found much smaller than the ion gyroradius and is close to theoretically predicted geometric mean of the ion and electron gyroradii. The width remains essentially the same when the magnetic field is filled … more

Date: December 1, 1990

Creator: Okuda, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Solar wind stream evolution

Highlights of the recent progress in understanding the problem of high speed stream evolution with increasing heliocentric distance are reviewed. Crucial to this understanding are the measurements made in the inner solar system by Helios and the outer solar system by Pioneers 10 and 11. When coupled with observations at 1 AU these measurements allow a testing of current theoretical models of stream evolution. 21 references.

Date: January 1, 1978

Creator: Gosling, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solar wind heavy ions from energetic coronal events

Ions heavier than those of He can be resolved in the solar wind with electrostatic E/q analyzers when the local thermal temperatures are low. Ordinarily this condition prevails in the low speed solar wind found between high speed streams, i.e. the interstream, IS, solar wind. Various ions of O, Si and Fe are resolved in IS heavy ion spectra. Relative ion peak intensities indicate that the O ionization state is established in the IS coronal source regions at approx. 2.1 x 10/sup 6/K while the st… more

Date: January 1, 1978

Creator: Bame, S.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Superposed epoch analysis of magnetospheric substorms using solar wind, auroral zone, and geostationary orbit data sets

A primary goal in solar wind-magnetosphere studies is to understand how and what role the solar wind plays in controlling the temporal sequence of events during substorms at many widely separated regions within the magnetosphere. Here, the average, correlated behavior of definitive solar wind, auroral zone, and geostationary orbit parameters during isolated substorms is examined. High time resolution (1 min) measurements of two solar wind quantities: B/sub z/ and VB/sub s/, two auroral electroj… more

Date: January 1, 1985

Creator: Bargatze, L.F.; Baker, D.N. & McPherron, R.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solar wind thermal electron distributions

Solar wind thermal electron distributions exhibit distinctive trends which suggest Coulomb collisions and geometric expansion in the interplanetary magnetic field play keys roles in electron transport. We introduce a simple numerical model incorporating these mechanisms, discuss the ramifications of model results, and assess the validity of the model in terms of ISEE-3 and Ulysses observations. Although the model duplicates the shape of the electron distributions, and explains certain other obs… more

Date: January 1, 1991

Creator: Phillips, J.L. & Gosling, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fluid modeling of magnetized plasmas

The simplified description given by fluid models of magnetized plasmas makes it possible to simulate large scale problems such as the interaction of the solar wind with the earth's magnetic field. However, the accurate numerical solution of the fluid equations is made more difficult by the singular nature of the flow when magnetic reconnection occurs. During substorms, for example, details of small features of the flow in the magnetotail appear to cause changes in the global solutions. New meth… more

Date: January 1, 1985

Creator: Brackbill, J.U.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hybrid simulations of a curved shock

No Description Available.

Date: January 1, 1989

Creator: Thomas, V. & Winske, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Magnetospheric Response to Solar Wind Variations

The time lagged response of the magnetosphere to solar wind variations has been determined using the linear prediction filtering method and 34 intervals of high time resolution IMP-8 solar wind data and auroral electrojet AL index data. The linear prediction filtering method is a powerful time series analysis technique which is utilized to produce a filter of time lagged response coefficients which estimates the most general linear relationship between magnetospheric activity and solar wind var… more

Date: April 1, 1985

Creator: Bargatze, L. F.; Baker, D. N. & McPherron, R. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Magnetic field draping about coronal mass ejecta

Fast coronal mass ejecta (CMEs) accelerate and deflect the slower moving solar wind plasma which piles up ahead of them as they propagate out through the heliosphere. This acceleration and deflection, in turn, causes the interplanetary magnetic field (IMF) imbedded in the upstream solar wind to drape about the ejecta. Draping should cause substantial out-of-the-ecliptic magnetic fields at some locations ahead of CMEs, and radial fields behind and along the flanks. At the Earth, draping can be a… more

Date: January 1, 1987

Creator: McComas, D.J. & Gosling, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department