Search Publications
The relationship of coronal mass ejections to streamers
Howard, R. A.; Dere, K. P.; Subramanian, Prasad +1 more
We have examined images from the Large-Angle and Spectrometric Coronagraph (LASCO) to study the relationship of coronal mass ejections (CMEs) to coronal streamers. We wish to test the suggestion [Low, 1996] that CMEs arise from flux ropes embedded in a streamer erupting and disrupting the streamer. The data span a period of 2 years near Sunspot mi…
Cyclotron resonance in coronal holes: 2. A two-proton description
Hollweg, Joseph V.
In a cold plasma, the ion-cyclotron mode does not extend above the proton cyclotron frequency. As a consequence, for waves propagating outward from the Sun, only protons that are moving slower than the mean proton wind speed can resonate with this mode. Thus only roughly half of the proton distribution function can be in resonance at any instant o…
Solar wind electrons: Parametric constraints
Goldstein, Bruce E.; Gary, S. Peter; Skoug, Ruth M. +1 more
Solar wind electrons are often observed to consist of two distinguishable components, a thermal, more dense core and a suprathermal, less dense halo. In this core/halo model linear Vlasov theory for the whistler heat flux instability predicts dimensionless heat flux thresholds which decrease as the electron core beta, β~∥c, increases. I…
Identification of trailing edge solar wind stream interfaces: A comparison of Ulysses plasma and composition measurements
Crooker, N. U.; Burton, M. E.; Smith, E. J. +2 more
Measurements of the specific entropy argument of the solar wind protons, T/nγ-1, reveal that nearly every occurrence of a high-speed stream seen at Ulysses in 1992-1993 is characterized by an abrupt interface at its trailing edge. These observations, made by the solar wind plasma instrument (SWOOPS), at a heliocentric range of 4.5 to 5 …
Amplitude evolution and rigidity dependence of the 26-day recurrent cosmic ray decreases: COSPIN/KET results
Kunow, H.; Bothmer, V.; Potgieter, M. S. +8 more
In the time interval extending from July 1992 to July 1994, Ulysses climbed from 10°S heliographic latitude up to over 70°S. During this time lapse, solar minimum conditions were gradually approached, which, in turn, led to stable and long-lasting corotating interaction regions (CIRs). The corotating particle events observed during this period, as…
Study of the latitudinal dependence of H I Lyman α and O VI emission in the solar corona: Evidence for the superradial geometry of the outflow in the polar coronal holes
Kohl, John L.; Cranmer, Steven R.; Dobrzycka, Danuta +2 more
We study the latitudinal distribution of the H I Lyman α and O VI (103.2 nm and 103.7 nm) line emission during the period of the Whole Sun Month campaign (August 10 to September 8, 1996) when the Sun was close to the minimum of its activity. The H I Lyman α and O VI line intensities appeared to be almost constant with latitude within the polar cor…
Relationship between Ulysses plasma observations and solar observations during the Whole Sun Month campaign
Luhmann, J. G.; Thompson, B. J.; Hoeksema, J. T. +7 more
In this report, we summarize measurements made by the plasma experiment on the Ulysses spacecraft during the period designated as ``Whole Sun Month'' (WSM, August 10 to September 8, 1996). This interval coincided with the return of solar wind variability at Ulysses. Ulysses was located at ~28°N heliographic latitude, at a heliocentric distance of …
Interplanetary scintillation measurements of the solar wind during Whole Sun Month: Comparisons with coronal and in situ observations
Thompson, B. J.; Biesecker, D. A.; Lazarus, A. J. +7 more
Two-site observations of interplanetary scintillation using the EISCAT facility can provide measurements of solar wind velocity at any point in the heliosphere between 15 and 120 solar radii (R). In this paper we discuss a series of observations made as part of the Whole Sun Month campaign (August 10 to September 8 1996) and compare the results wi…
Solar wind stream interfaces in corotating interaction regions: New SWICS/Ulysses results
Wimmer-Schweingruber, Robert F.; von Steiger, Rudolf; Paerli, Raoul
We have analyzed data from the solar wind ion composition spectrometer (SWICS)/Ulysses instrument taken between August 1996 and May 1997. In this period the Ulysses spacecraft traveled from 28° to 11°N and encountered a highly regular pattern of high-speed streams alternating with slow solar wind. Heliocentric distance varied between 4.3 and 5.1 a…
Three-dimensional reconstruction of UV emissivities in the solar corona using Ultraviolet Coronagraph Spectrometer data from the Whole Sun Month
Panasyuk, Alexander V.
UV coronal intensity data collected by the Ultraviolet Coronagraph Spectrometer on SOHO in a daily synoptic program during the Whole Sun Month are used to reconstruct the three-dimensional distribution of emissivities in the solar corona for H I Ly α and the O VI doublet at 1032 and 1037 Å. We discuss the specifics that complicate a tomographic re…