Search Publications
Ulysses electron distributions fitted with Kappa functions
Maksimovic, Milan; Riley, Pete; Pierrard, Viviane
We fit Kappa functions to 16,000 velocity distribution functions measured in the solar wind by the electron plasma instrument on board Ulysses. Statistically, the electron distributions are observed to have important high velocity tails in the fast solar wind but are closer to a Maxwellian in the slow wind. We also discuss how this result could su…
SWICS/Ulysses observations: The three-dimensional structure of the heliosphere in the declining/minimum phase of the solar cycle
Livi, S.; Woch, J.; Geiss, J. +5 more
The ESA/NASA spacecraft Ulysses provides the first in-situ observation of the solar wind at high solar latitudes. Data obtained with the Solar Wind Ion Composition Spectrometer (SWICS) during the first orbit of Ulysses around the Sun can be used to obtain a global view of the solar wind pattern within the heliosphere during the declining/minimum p…
Extension of coronal structure into interplanetary space
Habbal, Shadia Rifai; Woo, Richard
We investigate the extension and evolution of the solar corona into interplanetary space by comparing 1995 Ulysses radio occultation measurements of path-integrated electron density and density fluctuations measured between 21 and 32 Ro, with simultaneous white-light measurements made by the HAO Mauna Loa K-coronameter below 2.5 Ro…
The northern edge of the band of solar wind variability: Ulysses at ∼4.5 AU
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +4 more
Ulysses observations reveal that the northern edge of the low-latitude band of solar wind variability at ∼4.5 AU was located at N30° in the latter part of 1996 when solar activity was at a minimum. This edge latitude is intermediate between edge latitudes found during previous encounters with the band edge along different portions of Ulysses' pola…
Ulysses observations of the northward extension of the heliospheric current sheet
Balogh, A.; Forsyth, R. J.; Smith, E. J. +1 more
After passing through the northern polar regions of the heliosphere during the summer of 1995, the Ulysses spacecraft has been gradually returning towards lower equatorial latitudes, reaching 30°N in August 1996 at about which time low speed solar wind from the streamer belt was once again observed. This paper reports on the Ulysses magnetic field…
Particle acceleration at corotating reverse shocks in the southern hemisphere: Ulysses results
Balogh, A.; Forsyth, R. J.; Desai, M. I. +3 more
We have correlated the ∼1 MeV proton intensity (J) measured at corotating reverse shocks detected by Ulysses in the southern hemisphere with two parameters that characterise the strength of the shock. Between 6°-29°S J is essentially independent of the shock strength, whereas between 29°-41°S J is well correlated with the same. The poor correlatio…
Ulysses observations of a discrete wavepacket upstream of an interplanetary shock
Balogh, A.; Lucek, E. A.
We present a single example of a previously unidentified type of upstream wave structure, found several minutes ahead of a forward propagating, oblique interplanetary shock observed on day 6, 1992, using Ulysses magnetometer data. The wave appears as an isolated high frequency wavepacket associated with a larger scale compressive structure. In the…
The Ulysses north polar pass: Latitudinal gradients of anomalous cosmic ray O, N And Ne
Sanderson, T. R.; Marsden, R. G.; Trattner, K. J.
A key finding of the Ulysses mission has been the absence of large latitudinal gradients in the Anomalous Cosmic Ray (ACR) component. Studies using data from several satellites have consistently shown a small (∼ 2%/deg.) positive latitudinal gradient for anomalous O, N and Ne in the energy range 4 to 30 MeV/n, and even smaller gradients for ACR He…
Ulysses observations of short-period (≤30 Days) modulation of the galactic cosmic rays
Keppler, E.; Kunow, H.; Heber, B. +3 more
A frequency analysis of the short-period modulation of the GCR as seen by instruments aboard Ulysses shows interesting temporal variations. In particular, during an approximate five-month period from December 1993 to May 1994, the modulation was not the usual 26 days but more than 29 days. The CIR-associated MeV ions did not exhibit this period sh…
The Latitudinal Structure of the Solar Wind in the Vicinity of the Solar Equator near Solar Minimum: 1986 and Predictions for 1997
Gazis, P. R.
In situ observations by different spacecraft have shown that the heliospheric current sheet (HCS) is associated with a narrow band of low speed high density solar wind. The inclination of the HCS and the three-dimensional structure of solar wind streams is related to the inclination of the coronal neutral line. Observations from the Ulysses spacec…