Search Publications
Iron charge state distributions as an indicator of hot ICMEs: Possible sources and temporal and spatial variations during solar maximum
Lepri, S. T.; Zurbuchen, T. H.
It has been shown that Fe charge states greater than and equal to 16 are often observed in the presence of interplanetary coronal mass ejections (ICMEs) at 1 AU. These elevated charge states, representative of hot source regions on the Sun, provide an identifier of ICMEs independent of expansion processes and heliocentric distance. Using this new …
Differential velocity between solar wind protons and alpha particles in pressure balance structures
Sakurai, Takashi; Suess, Steven T.; Steinberg, John T. +1 more
Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advect…
Counterstreaming electrons in magnetic clouds near 5 AU
Forsyth, R.; Crooker, N. U.; Gosling, J. T. +2 more
Suprathermal electron pitch angle spectrograms were searched for counterstreaming signatures in 31 magnetic clouds identified in Ulysses data when the spacecraft was located ∼5 AU from the Sun. Under the assumption that counterstreaming indicates closed field lines, that is, field lines attached to the Sun at both ends, we find that the clouds ran…
Solar wind stream interaction regions without sector boundaries
Steinberg, J. T.; Goldstein, B. E.; Neugebauer, M. +2 more
During periods of high solar activity when there are many sources of solar wind on the solar disk, a spacecraft occasionally encounters consecutive solar wind streams with the same magnetic polarity. The low-speed wind in the region of interaction between the two streams exhibits many of the same features as, but has some differences from, the low…
A statistical study of oxygen freezing-in temperature and energetic particles inside magnetic clouds observed by Ulysses
Krupp, N.; Woch, J.; Rodriguez, L. +5 more
Interplanetary Coronal Mass Ejections (ICMEs) have proven to be very complex phenomena, not easy to unveil using a single set of observations. We combine Ulysses observations of medium energy particles, solar wind plasma parameters, magnetic field, and charge state distributions of heavy ions in order to identify and characterize CME ejecta in the…
Low-energy particle response to CMEs during the Ulysses solar maximum northern polar passage
Lario, D.; Reisenfeld, D. B.; Roelof, E. C. +2 more
Near the end of 2001, the Ulysses spacecraft transited the northern polar regions of the heliosphere, above heliographic latitudes of 71°N. During this period (September-November 2001), Ulysses remained immersed in polar coronal hole solar wind flow and observed five intense solar energetic particle events and five interplanetary coronal mass ejec…
Fast solar wind after the rapid acceleration
Breen, A. R.; Tokumaru, M.; Hayashi, K. +3 more
We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13-0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation…
Observations of cosmic ray electrons and positrons during the early stages of the A- magnetic polarity epoch
Clem, John; Evenson, Paul
As part of our ongoing investigation of the charge sign dependence in solar modulation, we measured the cosmic ray positron abundance (0.8 GeV to 4.5 GeV) and electron flux (20 MeV to 4.5 GeV) on balloon flights from Lynn Lake, Manitoba during August 2002. We find that the decrease in the positron abundance observed in 2000 persists in 2002. The l…
Anisotropy and Alfvénicity of hourly fluctuations in the fast polar solar wind
Neugebauer, M.
Ulysses magnetic and plasma data obtained in the fast polar solar wind are used to study the nature of fluctuations in the frequency range between the turbulent inertial range and the lower-frequency range dominated by quasi-static structures originating at the Sun. For daily variations of hourly averages of the magnetic field components the aniso…
New observations from Cassini and Ulysses of Jovian VLF radio emissions
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +2 more
Simultaneous observations of Jupiter's so-called reradiated VLF radio emission by the Cassini and Ulysses spacecraft confirm that the emission is radiated into all directions in a pulse or strobe light-like fashion. These observations rule out a source that corotates with the planet. Observations of the same VLF emission component during the Cassi…