Search Publications

The nature of comet Shoemaker-Levy 9 subnuclei from analysis of preimpact Hubble Space Telescope images

Mumma, Michael J.; Hahn, Joseph M.; Rettig, Terrence W. +2 more

We obtained Hubble Space Telescope (HST) Wide Field Planetary Camera images of comet Shoemaker-Levy 9 (S-L 9) prior to impact with Jupiter in 1994 to observe the effects of the Jovian gravitational field on the approaching fragments. The HST images were used to monitor the absolute brightness in the central regions of the comae, changes in the sur…

Upstream and downstream propagating waves generated by pickup ions near comet Halley

Glassmeier, K. -H.; Neubauer, F. M.; Krauklis, I. +3 more

It is well known that most of the Alfvén waves generated in the solar wind by cometary ion pickup are propagating upstream in the solar wind reference frame. However, the magnitude of the small proportion propagating downstream is extremely important because it controls the amount of ion acceleration driven by the second order Fermi process. The v…

Solar cycle dependence of the solar wind dynamics: Pioneer, Voyager, and Ulysses from 1 to 5 AU

Smith, Edward J.; Américo González-Esparza, J.

Magnetic field structure in the comet Grigg-Skjellerup pileup region

Coates, A. J.; Neubauer, F. M.; Israelevich, P. L. +1 more

The position of the Giotto spacecraft relative to comet Grigg-Skjellerup is found from the draping geometry based on the vector magnetic field data. It is shown that Giotto passed the cometary nucleus on the nightside. The behavior of the magnetic field vectors exhibits two different types in the pileup region. In the outer pileup region, the magn…

Low-energy particle oscillations and correlations with hydromagnetic waves in the Jovian magnetosphere: Ulysses measurements

Krupp, N.; Tsurutani, B. T.; Lanzerotti, L. J. +1 more

We report on measurements of energetic particle modulations (ions and electrons with energies E>50 keV) observed by the heliosphere instrument for spectra, composition, and anisotropy at low energies (HI-SCALE) aboard the Ulysses spacecraft that were associated with the only hydromagnetic (HM) wave event measured inside the Jovian magnetosphere…

Ulysses observations of corotation lags in the dayside Jovian magnetosphere: An evaluation of the hinged magnetodisc and magnetic anomaly models

Dougherty, Michele K.; Phillips, John L.; Hoogeveen, Gary W.

Ulysses observations during the inbound leg of the February 1992 encounter with Jupiter offer the opportunity to evaluate both the hinged magnetodisc and the magnetic anomaly models currently used to describe the Jovian magnetospheric corotation lag. Particle and field detectors on board Ulysses measure signatures of the current and plasma sheets.…

D/H and O-18/O-16 ratio in the hydronium ion and in neutral water from in situ ion measurements in comet Halley

Altwegg, K.; Balsiger, H.; Geiss, J.

The D/H ratio and the O-18/O-16 ratio in hydronium ions in the gas coma of comet Halley have been determined from ion data obtained by the high intensity sensor (HIS) of the ion spectometer (IMS) on board the spacecraft Giotto in 1986. The HIS instrument measured the reliable data for the water group ions over a large distance range from the nucle…

Ulysses observations of microstreams in the solar wind from coronal holes

Balogh, A.; McComas, D. J.; Goldstein, B. E. +2 more

During its south polar passage in 1994, the Ulysses spacecraft continuously sampled the properties of the solar wind emanating from the south polar coronal hole. At latitudes poleward of ~-60°, the solar wind speed had an average value of 764 km/s and a range of 700-833 km/s. The principal variations in the vector velocity were associated with eit…

Ulysses observation of a noncoronal mass ejection flux rope: Evidence of interplanetary magnetic reconnection

Balogh, A.; McComas, D. J.; Forsyth, R. J. +5 more

A well-defined, small-scale (~0.05 AU) magnetic flux rope was observed by Ulysses at about 5 AU in close proximity to a heat flux dropout (HFD) at the heliospheric current sheet (HCS). This magnetic flux rope is characterized by a rotation of the field in the plane approximately perpendicular to the ecliptic (and containing the Sun and the spacecr…

C⁺ pickup ions in the heliosphere and their origin

Geiss, J.; Gloeckler, G.; Fisk, L. A. +1 more

C⁺ pickup ions were discovered with the solar wind ion composition spectrometer flying on Ulysses. Whereas the other nonlocally occurring pickup ions are produced from the interstellar gas penetrating deep into the heliosphere, C⁺ comes from an ``inner source'' which is located at a solar distance of a few AU and extends over…