Search Publications
Detection of a γ-ray burst of very long duration and very high energy
Cline, T.; Hurley, K.; Fishman, G. J. +24 more
ALTHOUGH γ-ray bursts (GRBs) have been known for more than 20 years, their origin remains mysterious1. Suggestions have ranged from nearby colliding comets2 to merging neutron stars at cosmological distances3. The lack of any counterpart at wavelengths other than X-rays and γ-rays has posed a major problem in ident…
Interstellar dust in the heliosphere
Mann, I.; Morfill, G. E.; Gruen, E. +5 more
A flow of µm-sized interstellar grains has been identified with the Ulysses dust detector in the outer solar system at about 5 AU from the Sun. The observed flux is 1.5x10^-4^m^-2^/s of particles of mean mass 3x10^-13^g, which corresponds to a mass flux of 5x10^-17^g/m^2^/s. The particles on hyperbolic trajectories have radiants which are co…
Acceleration of interstellar pickup ions in the disturbed solar wind observed on Ulysses
Geiss, J.; Lanzerotti, L. J.; Roelof, E. C. +6 more
Acceleration of interstellar pickup H+ and He+ as well as of solar wind protons and alpha particles has been observed on Ulysses during the passage of a corotating interaction region (CIR) at ~4.5 AU. Injection efficiencies for both the high thermal speed interstellar pickup ions (H+ and He+) and the low…
Ulysses field and plasma observations of magnetic holes in the solar wind and their relation to mirror-mode structures
Goldstein, Bruce E.; Neugebauer, Marcia; Smith, Edward J. +3 more
The term ``magnetic hole'' has been used to denote intervals when the magnitude of the interplanetary magnetic field drops to a few tenths, or less, of its ambient value for a time that corresponds to a linear dimension of tens to a few hundreds of proton gyro-radii. Data obtained by the Ulysses magnetometer and solar wind analyzer have been combi…
Interstellar oxygen, nitrogen and neon in the heliosphere
Geiss, J.; Galvin, A. B.; Mall, U. +3 more
Oxygen, nitrogen and neon pick-up ions of interstellar origin were detected for the first time with the Solar Wind Ion Spectrometer (SWICS) on board Ulysses. The interstellar origin of these ions is established by the following criteria: (a) they are singly charged, (b) they have the broad velocity distributions characteristic of pick-up ions, wit…
The relationship between interplanetary discontinuities and Alfvén waves: Ulysses observations
Balogh, A.; Tsurutani, B. T.; Smith, E. J. +7 more
The rate of occurrence of interplanetary discontinuities (ROID) is examined using Ulysses magnetic field and plasma data from 1 to 5 AU radial distance from the Sun and at high heliographic latitudes. We find two regions where the ROID is high: in stream-stream interaction regions and in Alfvén wave trains. This latter feature is particularly obvi…
The whistler heat flux instability: Threshold conditions in the solar wind
Gary, S. Peter; Scime, Earl E.; Phillips, John L. +1 more
Solar wind electrons are observed often to consist of two components: a core and a halo. The anisotropies and relative average speed of these two components correspond to a heat flux that has the potential to excite several different electromagnetic instabilities; wave-particle scattering by the resulting enhanced fluctuations can limit this heat …
Ulysses at 50° south: constant immersion in the high-speed solar wind
Balogh, A.; Hoeksema, J. T.; McComas, D. J. +7 more
We present speed observations from the Ulysses solar wind plasma experiment through 50° south latitude. The pronounced speed modulation arising from solar rotation and the tilt of the heliomagnetic current sheet has nearly disappeared. Ulysses is now observing wind speeds in the 700 to 800 km s-1 range, with a magnetic polarity indicati…
Charged-Particle Motion in Multidimensional Magnetic Field Turbulence
Giacalone, J.; Jokipii, J. R.
We present a new analysis of the fundamental physics of charged-particle motion in a turbulent magnetic field using a numerical simulation. The magnetic field fluctuations are taken to be static and to have a power spectrum which is Kolmogorov. The charged particles are treated as test particles. It is shown that when the field turbulence is indep…
A new class of forward-reverse shock pairs in the solar wind
McComas, D. J.; Forsyth, R. J.; Goldstein, B. E. +4 more
A new class of forward-reverse shock pairs in the solar wind has been discovered using Ulysses observations at high heliographic latitudes. These shock pairs are produced by expansion of coronal mass ejections, CMEs, that have internal pressures that are higher than, and speeds that are comparable to, that of the surrounding solar wind plasma. Of …