Search Publications
Energetic particle composition variations during the March 1991 events measured with the Ulysses EPAC instrument
Krupp, N.; Woch, J.; Fränz, M. +9 more
We report on energetic particle measurements obtained with the EPAC instrument on board the Ulysses spacecraft during March 1991, when a series of important flares occurred at the Sun. The EPAC instrument measures electrons (0.1-0.38 MeV), protons (0.3-1.5 MeV) and heavy ions (0.2-6.0 MeV/N). We discuss the time interval March 22 through March 29 …
Observation of non-drifting radio emissions associated with the intense solar activity in March 1991
Stone, R. G.; Fainberg, J.; Reiner, M. J.
Three very unusual radio bursts, separated in time by 4 hours and 35 minute-intervals were observed on March 28, 1991 by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. Although they are preceded by drifting type III bursts at high frequencies, they show no frequency drift at frequencies from 52 kHz down to 16 kHz. In additi…
Unusual radio and plasma wave phenomena observed in March 1991
Stone, R. G.; Fainberg, J.; Reiner, M. J.
During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Som…
The effect of the shock of 15:43 UT March 23, 1991 on 50 keV to 5 MeV ions at Ulysses
Simnett, G. M.; Armstrong, T. P.; Roelof, E. C. +2 more
The intensities, angular distributions, and energy spectra of 50 keV to 5 MeV ions are examined in the several hour time interval when an interplanetary shock passed the Ulysses spacecraft. The increase in intensity, evolution of pitch angle distribution from upstream flow away from the shock to a post-shock “pancake” distribution, the earlier arr…
Diffusive shock acceleration and the March 1991 solar events
Krupp, N.; Keppler, E.; Korth, A. +7 more
Spectral and anisotropy measurements are reported for protons between 0.5 and 1.4 MeV during the particle increases associated with the passage of 3 interplanetary shocks past Ulysses between March 19 and March 31 1991. The data are interpreted in terms of diifusive shock acceleration in the travelling solar induced disturbances to the solar plasm…
Gas release from ice/dust mixtures
Krankowsky, D.; Mauersberger, K.; Hesselbarth, P. +4 more
Gas fluxes from insolated ice/dust mixtures were measured by pressure gauges and a mass spectrometer placed one meter in front of the sample. As soon as the insolation of about one solar constant was started a fast rise in H2O and CO2 emissions from the fresh surface was observed. Thereafter gas fluxes slowly decreased. When …
Giotto's Mission to planet Earth
Glassmeier, K. -H.; Neubauer, F. M.; Ungstrup, E. +9 more
After its successful encounter with comet P/Halley and a four-years hibernation period ESA's Giotto spacecraft has been reactivated in February 1990 and performed the first-ever Earth gravity-assisted maneuver on July 2, 1990 to be retargeted for comet P/Grigg-Skjellerup. This swing-by is of unique scientific interest due to Giotto's hyperbolic, h…
Hypervelocity dust particle impacts observed by the Giotto Magnetometer and Plasma Experiments
Coates, A. J.; Glassmeier, K. -H.; Neubauer, F. M. +3 more
We report thirteen very short events in the magnetic field of the inner magnetic pile-up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the s…
Analysis of suprathermal electron properties at the magnetic pile-up boundary of comet P/Halley
Anderson, K. A.; Neubauer, F. M.; Rème, H. +10 more
Among the plasma discontinuities detected by the GIOTTO spacecraft around comet P/Halley, the Magnetic Pile-up Boundary, located at about 135,000 km from the nucleus, has a sharpness which was not foreseen by theoretical models. At this boundary, which marks the beginning of the region where the field lines draped around the nucleus have been pile…
Cometary H2 + and solar wind He2+ dynamics across the Halley cometopause
Balsiger, H.; Geiss, J.; Ip, W. -H. +4 more
Two Mass/Charge (M/Q) ≈ 2 distributions were observed by the Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) during the encounter with comet Halley. The first, present throughout the encounter, is identified as solar wind He2+. The second, detectable only within ∼6 × 105 km of the nucleus, is identified…