Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere

Keppler, E.; Fränz, M.; Korth, A.; Reuss, M. K.; Blake, J. B.; Seidel, Robert; Quenby, J. J.; Witte, M.

doi:10.1126/science.7754379

Cited by 28 publications

(16 citation statements)

References 25 publications

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“…terpret recent particle modulation experiments aboardUlysses[Keppler et al, 1995;Simpson et al, 1995].…”

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confidence: 71%

Corotating shock accelerated particles guided by wavy spiral magnetic fields in the solar wind at high heliographic latitudes

Lou

1996

Geophysical Research Letters

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We propose the persistent presence of randomly fluctuating, large‐amplitude, long‐timescale wavy spiral magnetic fields in the solar wind at all heliographic latitudes. These Alfvénic fluctuations can be generated by gradual evolution of solar coronal holes or by interplanetary Kelvin‐Helmholtz instabilities occurring around the two conical interfaces at ∼±30° where strong wind shears appear quasi‐periodically during the solar minimum. Using this scenario, we offer interpretations for several recent high‐latitude observations of quasi‐periodic (i.e., ∼26.6 days) energetic particle and cosmic ray modulations from Energetic Particle Composition instrument and Cosmic Ray and Solar Particle Investigation sensor systems aboard Ulysses spacecraft.

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“…terpret recent particle modulation experiments aboardUlysses[Keppler et al, 1995;Simpson et al, 1995].…”

mentioning

confidence: 71%

Corotating shock accelerated particles guided by wavy spiral magnetic fields in the solar wind at high heliographic latitudes

Lou

1996

Geophysical Research Letters

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“…It will be allowed for in drawing the conclusions of this work. Figure 1 shows the raw data from the ELH channel from 1992, after Jovian electrons become unimportant, until mid-1994 when the highest solar latitude is reached (a full discussion of all EPAC observations at high latitudes can be found in Keppler et al, 1995). We make no attempt to remove solar electron events.…”

Section: Observationsmentioning

confidence: 99%

A ?Ulysses? cosmic-ray latitude gradient observation and modulation models

et al. 1996

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The 'EPAC' instrument on Ulysses is sensitive to relativistic cosmic rays when far from Jupiter and in the absence of energetic solar particles. Measurement of the latitude gradient of these particles, after correction for time variations, has been made for the 1993-1994 south polar pass. The average magnitude of the gradient is about the same or smaller than predicted by a model which includes full gradient drift. However, the latitude dependence of the solar plasma output into interplanetary space (including fast-stream and magnetic turbulence effects) seems to be important in determining the magnitude of modulation.

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“…Whenever the particle flux is measured in many spatial directions (e.g. [4,12,15]) covering the observational sphere, the method of spherical harmonics expansion of the flux is applied and the coefficients of the expansion are interpreted as measures of the flux anisotropy of the particles [1,[16][17][18][19][20][26][27][28]. The study of the anisotropy components is instructive but far from a fluid description of the particles distribution.…”

Section: Introductionmentioning

confidence: 99%