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Ulysses plasma observations in the Jovian magnetosheath
Thomsen, M. F.; Smith, E. J.; Bame, S. J. +2 more
The solar wind plasma experiment aboard the Ulysses spacecraft, including separate ion and electron instruments, measured the plasma properties of the Jovian magnetosheath during the February 1992 encounter with Jupiter. Seven separate magnetosheath intervals were observed, as well as four bow shock crossings and numerous encounters with the magne…
Variability of [O I] 6300-Å emission near Io
Smyth, W. H.; Scherb, F.
Observations of [O I] 6300-Å emission near Io have been obtained in 1990, 1991, and 1992 by the National Solar Observatory staff using the solar-stellar spectrograph on the McMath-Pierce telescope at Kitt Peak. High-resolution spectra with a resolving power of about 1.2×105 were obtained with an integration time of 10-15 min each. The v…
High-velocity tails on the velocity distribution of solar wind ions
Geiss, J.; Gloeckler, G.; Wilken, B. +2 more
Recent observations of the solar wind using the SWICS instrument on the Ulysses spacecraft have shown the presence of high-velocity ``tails'' on the velocity distribution of protons. Similar features have also been observed on the velocity distributions of helium and oxygen ions. Of the order of 1% of the solar wind density is involved in these ta…
Optically thin H Lyman alpha production on outer planets: Low-energy proton acceleration in parallel electric fields and neutral H atom precipitation from ring current
Bhardwaj, A.; Singhal, R. P.
A Monte Carlo model has been constructed to describe the energization and energy degradation of low-energy protons in an H2 atmosphere in the presence of parallel electric field. The energy spectrum of Ly α collision events is employed to determine the volume emission rate (VER) of H Ly α emissions. Numerical experiments have been perfo…
Mass loading and velocity diffusion models for heavy pickup ions at comet Grigg-Skjellerup
Coates, A. J.; Neubauer, Fritz M.; Johnstone, A. D. +1 more
We compare model predictions of cometary water group ion densities and the solar wind slow down with measurements made by the Giotto Johnstone plasma analyzer implanted ion sensor at the encounter with comet Grigg-Skjellerup (G-S) on July 10, 1992. The observed slope of the ion density profile on approach to the comet is unexpectedly steep. Possib…
Introduction to the Ulysses encounter with Jupiter
Smith, Edward J.; Wenzel, Klaus-Peter
The Ulysses spacecraft encountered Jupiter in February 1992, passing within 6.31 radii of the planet. For approximately 8 days it was inside the Jovian magnetosphere, and for several days before and after that, Ulysses was in the interaction regions formed by the solar wind (the magnetosheath and boundary layer). The inbound trajectory was at a ~1…
An interpretation of the broadband VLF waves near the Io torus as observed by Ulysses
Kaiser, M. L.; Desch, M. D.; Farrell, W. M. +3 more
The requirements for the Ulysses trajectory to attain high ecliptic latitudes using a Jovian gravitational assist resulted in a fortuitous passage through the Io torus region. Specifically, the spacecraft spend may hours at latitudes just above the torus. During this time the low-frequency cutoff of an ordinary mode (O mode) emission allowed a det…
MHD modeling applied to Giotto encounter with comet P/Grigg-Skjellerup
Neubauer, Fritz M.; Wegmann, R.; Schmidt, H. U.
First from a one-dimensional MHD model we derive estimates for position and shape of the bow shock applicable for arbitrary magnetosonic Mach numbers >1 in the solar wind. This generalization is important in the case of the Giotto encounter with P/Grigg-Skjellerup with the unusual interplanetary magnetic field (IMF) of 18 nT. We compare three-d…
ULF waves in the Io torus: Ulysses observations
Forsyth, R. J.; Rezeau, L.; Lin, Naiguo +7 more
Throughout the Io torus, Ulysses has observed intense ULF wave activity in both electric and magnetic components. Such ULF waves have been previously suggested as the source of ion precipitation leading to Jovian aurorae. The peaks of the wave spectra are closely related to the ion cyclotron frequencies, which is evidence of the waves being ion cy…
Sounder stimulated Dn resonances in Jupiter's Io plasma torus
MacDowall, R. J.; Stone, R. G.; Fainberg, J. +2 more
On February 8, 1992, the Ulysses spacecraft passed through Jupiter's Io plasma torus, where rich spectra of narrow-band resonances were stimulated by the relaxation sounder of the Ulysses unified radio and plasma wave (URAP) instrument. Since the gyrofrequency fg is comparable to the plasma frequency fp in the Io torus, it wa…