Search Publications
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…
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…
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 …
A forward-reverse shock pair in the solar wind driven by over-expansion of a coronal mass ejection: Ulysses observations
Balogh, A.; McComas, D. J.; Goldstein, B. E. +5 more
A previously unidentified type of solar wind forward-reverse shock pair has been observed by Ulysses at 4.64 AU and S32.5°. In contrast to most solar wind forward-reverse shock pairs, which are driven by the speed difference between fast solar wind plasma and slower plasma ahead, this particular shock pair was driven purely by the over-expansion o…
3-D Simulation of high-latitude interaction regions: Comparison with Ulysses results
Gosling, J. T.; Pizzo, V. J.
A three-dimensional (3-D) magnetohydrodynamic (MHD) numerical model is used to simulate the global evolution of a steady, tilted-dipole solar wind flow configuration similar to that prevalent in interplanetary space in 1993. Systematic latitudinal changes in the structure of a corotating interaction region (CIR) near 5 AU is shown to agree well wi…
Corotating particle enhancements out of the ecliptic plane
Simnett, G. M.; Tappin, S. J.; Roelof, E. C. +1 more
We have studied > 40 keV ion and electron enhancements seen at Ulysses from a series of corotating interaction regions (CIR), from mid-1992 until the end of 1993. The event intensity increased up to latitude 20°S after that the ion flux maxima decreased by ∼23%/deg while the electron maxima decreased more erratically, and more slowly, during th…
Magnetic reconnection ahead of a coronal mass ejection
McComas, D. J.; Forsyth, R. J.; Phillips, J. L. +3 more
On 29 November 1990 the Ulysses spacecraft passed through a series of interplanetary structures which suggest that reconnection had occurred on open field lines ahead of a coronal mass ejection (CME), changing the magnetic topology of the upstream region. We observe in sequence 1) a heat flux dropout, 2) a region of counterstreaming halo electrons…
Ulysses high-latitude observations of ions accelerated by co-rotating interaction regions
Balogh, A.; Forsyth, R. J.; Goldstein, B. E. +3 more
We present observations of energetic ions (E∼1 MeV) from the Ulysses spacecraft during its first pass from the ecliptic plane to the southern high-latitude regions of the heliosphere. At latitudes less than ∼13°S Ulysses was completely immersed in the heliomagnetic streamer belt, and observed a ∼1 MeV proton intensity which showed little evidence …
The speeds of coronal mass ejections in the solar wind at mid heliographic latitudes: Ulysses
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +3 more
Six CMEs have been detected in the Ulysses plasma observations poleward of S31°. The most striking aspect of these mid-latitude CMEs was their high speeds; the overall average speed of these CMEs was ∼ 740 km s-1, which was comparable to that of the rest of the solar wind at these latitudes. This average CME speed is much higher than av…
Concentration of interstellar pickup H+ and He+ in the solar wind
Geiss, J.; Giacalone, J.; Gloeckler, G. +1 more
We present observations of interstellar pickup hydrogen and helium in the solar wind which show large, highly-correlated fluctuations in flux which are not correlated significantly with the solar-wind hydrogen flux. The correlation of the fluctuations in the two species implies that the fluctuations are caused by transport after ionization. The la…