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Global imaging of Mars by Hubble space telescope during the 1995 opposition
Bell, James F.; Wolff, Michael J.; Clancy, R. Todd +3 more
Hubble space telescope (HST) imaging of Mars near the 1995 opposition resulted in excellent synoptic-scale images of the planet during the spring season in the northern hemisphere. Because this season coincides with the aphelion position of Mars in its orbit, it is therefore the most difficult for ground based observation because of the relatively…
Heliospheric plasma sheets as small-scale transients
Balogh, A.; Crooker, N. U.; Burton, M. E. +2 more
Ulysses plasma and magnetic field data from the ecliptic plane near 1 AU signaling multiple heliospheric plasma sheets across a sector boundary are analyzed in order to determine their geometrical configuration. The plasma sheets coincided with a region of sporadic heat flux dropouts and planar magnetic structure. The plane of the structure was in…
Properties of arc-polarized Alfvén waves in the ecliptic plane: Ulysses observations
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +3 more
Ulysses observations of the interplanetary magnetic field reveal well-ordered rotations on the timescale of several hours. These have been previously identified as ``arc-polarized'' Alfvén waves. Rotational discontinuities (RDs) are often an integral part of the wave. This study focuses on a statistical description of these rotations (ARCs) in the…
Plasma flow in the Jovian magnetosphere and related magnetic effects: Ulysses observations
Dougherty, M. K.; Balogh, A.; Forsyth, R. J. +6 more
The plasma flow in Jupiter's magnetosphere observed during the Ulysses flyby is compared with previous Pioneer, Voyager and ground-based observations. These data show that near-rigid corotation is enforced in the inner magnetosphere, but that the azimuthal flow plateaus at 150-300 kms-1 in the middle magnetosphere plasma sheet beyond ~2…
Mars ozone measurements near the 1995 aphelion: Hubble space telescope ultraviolet spectroscopy with the faint object spectrograph
Wolff, Michael J.; Clancy, R. Todd; James, Philip B. +4 more
Ultraviolet (225-330 nm) spectral scans of Mars were obtained with the Hubble space telescope (HST) faint object spectrograph (FOS) in February of 1995. These spectra yield ozone column abundances, cloud opacities (0.2-0.4 at low latitudes), and polar seasonal ice albedos from southern midlatitudes to northern high latitudes on Mars. At the time o…
Perpendicular transport in shock acceleration
Giacalone, J.; Jokipii, J. R.
We consider the foundations of charged-particle acceleration at collisionless shocks in which the average magnetic field is perpendicular to the shock-normal direction. Our shock model, which is a numerical integration of the trajectories of an ensemble of test particles in specified shock fields, includes an isotropic and homogeneous, Kolmogorov-…
Ulysses observations of whistler waves at interplanetary shocks and in the solar wind
Forsyth, R.; Balogh, A.; MacDowall, R. J. +4 more
This study of whistler wave emission observed by the Ulysses Unified Radio and Plasma Wave (URAP) experiment between 1 and 5 AU is a complement to previous studies of whistler waves observed by the Helios spacecraft between 0.3 and 1 AU. The Helios spacecraft continuously detected a background of whistlers close to the Sun, and this background was…
The tilts of corotating interaction regions at midheliographic latitudes
Riley, Pete; Gosling, J. T.; Pizzo, V. J. +1 more
Previous analysis of midlatitude corotating interaction regions (CIRs) observed by Ulysses in the southern heliosphere has revealed that the flow downstream of the forward (F) shock (or wave) on the leading edge of a CIR generally turns northward and into the direction of planetary motion (westward), while the flow downstream of the reverse (R) sh…
Magnetic field signatures of unevolved turbulence in solar polar flows
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +1 more
Between late 1993 and the middle of 1994, Ulysses stayed almost constantly within flows from the Sun's southern polar coronal hole, traveling from 44°S to 69°S heliolatitude and between 4.0 and 2.9 AU from the Sun. Magnetic field observations within this region reveal a very different medium from that at similar heliocentric distances near the ecl…
Heating of the thermal electrons in the coma of comet P/Halley
Geiss, Johannes; Altwegg, Kathrin; Balsiger, Hans +1 more
In the inner coma of a comet the total ion (or electron) density results from an equilibrium between ion production and ion destruction. The ions are mainly produced by photoionization of cometary gas, whereas the main destruction process is dissociative recombination of molecular ions with electrons. The reaction rate for the recombination depend…