Search Publications
Disappearance of the heliospheric sector structure at Ulysses
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +6 more
In May, 1993, the heliospheric current sheet (HCS) ceased to be seen by the Ulysses spacecraft at a heliocentric latitude of ∼30° S and distance of 4.7 AU. The disappearance of the HCS coincided with the solar wind speed remaining >560 km/s and with the disappearance of one of four interaction regions previously seen on each solar rotation. The…
Counterstreaming suprathermal electron events upstream of corotating shocks in the solar wind beyond ∼2 Au: Ulysses
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +3 more
Enhanced fluxes of suprathermal electrons are commonly observed upstream of corotating forward and reverse shocks in the solar wind at heliocentric distances beyond ∼2 AU by the Los Alamos plasma experiment on Ulysses. The average duration of these events, which are most intense immediately upstream from the shocks and which fade with increasing d…
Discrete wave packets at the proton cyclotron frequency at comet P/Halley
Neubauer, F. M.; Mazelle, C.
We present in this letter the first experimental evidence for wave packets near the local proton cyclotron frequency in the plasma environment of a comet. The observations have been made by the GIOTTO magnetometer experiment (MAG) around comet P/Halley on both sides of closest approach. The waves are always left-handed in the spacecraft frame, ell…
The evolution of the interplanetary sector structure in 1992
Balogh, A.; Forsyth, R. J.; Smith, E. J. +1 more
The unique vantage point of the Ulysses spacecraft throughout 1992 and the beginning of 1993, at a close to constant heliocentric distance of about 5 AU and a slowly varying heliographic latitude from 5° to 30° south is used to describe and discuss the evolution of the sector structure of the interplanetary magnetic field during the declining phas…
Pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Winningham, J. D.; Borg, H. +9 more
The density and velocity distribution of cometary water group ions was measured by the Giotto spacecraft in the regions upstream and downstream of the ‘bow shock’ at comet Grigg-Skjellerup. The results show that the distributions of ions are ring-like until quite close to the shock, the timescales for pitch angle and energy diffusion appear simila…
Prediction of the heliospheric current sheet tilt: 1992 - 1996
Hoeksema, J. T.; McComas, D. J.; Suess, S. T.
Heliospheric current sheet tilt evolves systematically over the solar cycle. Here we show that this evolution is different than the sunspot cycle and that tilt for the period 1992 - 1996 can be predicted using persistence. That is, the tilt over the coming cycle will be the same as for the past cycle. The Ulysses spacecraft has passed Jupiter and …
Source characteristics and locations of hectometric radio emissions from the northern Jovian hemisphere
Stone, R. G.; Fainberg, J.; Reiner, M. J.
Northern Jovian hectometric (HOM) radio emissions, detected from high Jovian latitudes by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft, were observed at all Jovian longitudes. This emission was observed to be predominantly right-hand circularly polarized, but some left-hand circular polarization was observed implyi…
Ulysses observations of auroral hiss at high Jovian latitudes
Bame, S. J.; Kellogg, P. J.; MacDowall, R. J. +8 more
During the Ulysses flyby of Jupiter, a whistler-mode emission was periodically detected by the Unified Radio and Plasma wave (URAP) experiment during intervals when the spacecraft extended to high magnetic latitudes. The signal was detected between the local electron plasma frequency and lower hybrid resonance and appears as a funnel-shaped struct…
The polar heliospheric magnetic field
Suess, S. T.; Nerney, Steven
We describe the large-scale magnetic field morphology in the heliosheath. A simple argument, which depends only on the interstellar wind flowing nearly in the solar equatorial plane, shows that polar heliospheric magnetic fieldlines never approach the heliopause and therefore are accessible to galactic cosmic rays only through perpendicular diffus…
Low-energy solar electrons and ions observed at Ulysses February-April, 1991: The inner heliosphere as a particle reservoir
Simnett, G. M.; Tappin, S. J.; Lanzerotti, L. J. +3 more
Ulysses observations at 2.5 AU of 38-315 keV electrons and 61-4752 keV ions during February-April 1991 suggest in several ways that, during periods of sustained high solar activity, the inner heliosphere serves as a “reservoir” for low-energy solar particles. Particle increases were not associated one-to-one with large X-ray flares because of thei…