Search Publications
Ulysses COSPIN observations of cosmic rays and solar energetic particles from the South Pole to the North Pole of the Sun during solar maximum
Balogh, A.; Kunow, H.; Posner, A. +10 more
In 2000-2001 Ulysses passed from the south to the north polar regions of the Sun in the inner heliosphere, providing a snapshot of the latitudinal structure of cosmic ray modulation and solar energetic particle populations during a period near solar maximum. Observations from the COSPIN suite of energetic charged particle telescopes show that lati…
Imprints from the solar cycle on the helium atom and helium pickup ion distributions
Fahr, H. J.; Bzowski, M.; Rucinski, D.
Neutral interstellar helium atoms penetrate into the solar system almost unaffected by gas-plasma interactions in the heliospheric interface region, and thus can be considered as carriers of original information on the basic parameters (like density, temperature, bulk velocity) of the Very Local Interstellar Medium (VLISM). Such information can no…
Delay in solar energetic particle onsets at high heliographic latitudes
Balogh, A.; Krucker, S.; Dalla, S. +9 more
Ulysses observations have shown that solar energetic particles (SEPs) can easily reach high heliographic latitudes. To obtain information on the release and propagation of SEPs prior to their arrival at Ulysses, we analyse the onsets of nine large high-latitude particle events. We measure the onset times in several energy channels, and plot them v…
Charge-sign dependent modulation in the heliosphere over a 22-year cycle
Fichtner, H.; Ferreira, S. E. S.; Potgieter, M. S. +1 more
A time-dependent model based on a numerical solution of Parker's transport equation is used to model the modulation of cosmic ray protons, electrons and helium for full 11-year and 22-year modulation cycles using a compound approach. This approach incorporates the concept of propagating diffusion barriers based on global increases in the heliosphe…
How did the solar wind structure change around the solar maximum? From interplanetary scintillation observation
McComas, D. J.; Elliott, H. A.; Tokumaru, M. +5 more
Observations from the second Ulysses fast latitude scan show that the global structure of solar wind near solar maximum is much more complex than at solar minimum. Soon after solar maximum, Ulysses observed a polar coronal hole (high speed) plasma with magnetic polarity of the new solar cycle in the Northern Hemisphere. We analyze the solar wind s…
Dynamical evolution of the inner heliosphere approaching solar activity maximum: interpreting Ulysses observations using a global MHD model
Riley, P.; Linker, J. A.; Mikic, Z.
In this study we describe a series of MHD simulations covering the time period from 12 January 1999 to 19 September 2001 (Carrington Rotation 1945 to 1980). This interval coincided with: (1) the Sun's approach toward solar maximum; and (2) Ulysses' second descent to the southern polar regions, rapid latitude scan, and arrival into the northern pol…
Magnetic topology of coronal mass ejection events out of the ecliptic: Ulysses/HI-SCALE energetic particle observations
Sarris, E. T.; Malandraki, O. E.; Tsiropoula, G.
Solar energetic particle fluxes (Ee > 38 keV) observed by the ULYSSES/HI-SCALE experiment are utilized as diagnostic tracers of the large-scale structure and topology of the Interplanetary Magnetic Field (IMF) embedded within two well-identified Interplanetary Coronal Mass Ejections (ICMEs) detected at 56° and 62° south heliolatitudes by ULYSSE…
The global heliospheric magnetic field polarity distribution as seen at Ulysses
Balogh, A.; Jones, G. H.
The Ulysses spacecraft is in a near-polar solar orbit with a period of 6.2 years. The heliospheric magnetic field polarity detected by Ulysses from its 1992 Jupiter encounter to the current time is presented, following ballistic mapping of the polarity information to the solar wind source surface, at approximately 2.5 solar radii. The spacecraft's…
Consequences of the Solar System passage through dense interstellar clouds
Fahr, H. J.; Yeghikyan, A. G.
Several consequences of the passage of the solar system through dense interstellar molecular clouds are discussed. These clouds, dense (more than 100 cm-3), cold (10-50 K) and extended (larger than 1 pc), are characterized by a gas-to-dust mass ratio of about 100, by a specific power grain size spectrum (grain radii usually cover the range 0.001-3…
Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: Ulysses COSPIN/KET and neutron monitor network observations
Kunow, H.; Heber, B.; Müller-Mellin, R. +4 more
Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The…