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Low energy anomalous ions at northern heliolatitudes

Lanzerotti, L. J.; Maclennan, C. G.

Measurements of the anomalous component of nitrogen, oxygen, and neon ions (∼0.5-8 MeV/nucl.) at northern heliolatitudes by the HI-SCALE instrument on the Ulysses spacecraft show that the energy spectra of these ions are essentially flat from the highest heliolatitudes (80° N) to near the ecliptic plane. For energies from 1-8 MeV/nucl., the northe…

Observations of galactic cosmic ray modulation during Earth-directed coronal mass ejections

Valtonen, E.; Riihonen, E.; Teittinen, M. +3 more

We describe three cosmic-ray decreases observed by the energetic particle telescope ERNE on board SOHO spacecraft during the period January-May, 1997. The decreases in cosmic-ray proton intensities in the energy range above 50 MeV were observed after the passage of interplanetary shocks on February 9, April 10, and May 15. All the shocks were prod…

Comment on: “Polar plumes and fine-scale coronal structures — On the interpretation of coronal radio sounding data” by Pätzold and Bird

Habbal, Shadia Rifai; Woo, Richard

The solar wind alpha-particle content as a clue for the origin of slow flows

Bavassano, B.; Pietropaolo, E.; Bruno, R.

Some aspects of the variation of the alpha-particle abundance in the solar wind are studied using Ulysses data. We focus on the first mid-latitude phase of the mission, when the spacecraft intermittently enters the fast high-latitude wind, and on the region around the first perihelion passage, when low-latitude wind in conditions of low solar acti…

Wave power dropouts associated with radial field intervals in high speed solar wind

Balogh, A.; McComas, D. J.; Horbury, T. S. +1 more

Examination of 770 days of heliospheric magnetic field data recorded within polar solar wind by the Ulysses spacecraft revealed a number of occasions when the wave power decreased by more than an order of magnitude for several hours. These power dropouts were found to be associated with intervals when the magnetic field was closely aligned with th…

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 R_o, with simultaneous white-light measurements made by the HAO Mauna Loa K-coronameter below 2.5 R_o…

Detection of SO₂ on Callisto with the Hubble Space Telescope

Johnson, Robert E.; McGrath, Melissa A.; Noll, Keith S. +1 more

We have detected SO₂ in ultraviolet spectra of Callisto obtained with the Hubble Space Telescope's Faint Object Spectrograph. An absorption band centered at 280 nm appears in the spectrum of Callisto's leading hemisphere, but is not apparent in the spectrum of the trailing hemisphere. The band is similar to the SO₂ band on Eu…

The Pele Plume (Io): Observations with the Hubble Space Telescope

Ballester, Gilda E.; McGrath, Melissa A.; Spencer, John R. +3 more

In July 1996, with the Hubble Space Telescope (HST), we observed the Pele plume silhouetted against Jupiter at a wavelength of 0.27µm, the first definitive observation of an Io plume from Earth. The height, 420 ± 40 km, was greater than any plume observed by Voyager. The plume had significantly smaller optical depth at 0.34 and 0.41µm, where it wa…