Search Publications
Ulysses in the south polar cap at solar maximum: Heliospheric magnetic field
Balogh, A.; McComas, D. J.; Forsyth, R. J. +1 more
Observations during the recent ascent of Ulysses to the south polar region are reported. Large variations in field magnitude are associated principally with solar wind interaction regions. The observed spiral angle agrees reasonably well with the Parker model. The magnetic flux, the product of the radial field component and the square of the radia…
Recurrent flare/CME events from an emerging flux region
Nitta, Nariaki V.; Hudson, Hugh S.
We report on six recurrent ‘halo’ coronal mass ejections (CMEs) that occurred (in November 2000) during a 60-hour period in clear association with major flares in an active region on the solar disk. The region was undergoing dynamic restructuring due to flux emergence. The flares were not long-decay events (LDEs) in terms of soft X-ray light curve…
Direct measurement of winds on Titan
Fast, Kelly E.; Hewagama, Tilak; Kostiuk, Theodor +4 more
We report the first direct measurement of wind velocity in the atmosphere of Titan, one of only two examples in our solar system of a slowly-rotating body with a dense atmosphere and a prime target of the Cassini mission. Zonal wind velocity was determined from Doppler shift of ethane lines emitted from Titan's stratosphere (∼0.1-7 mbar) measured …
Generation mechanism for magnetic holes in the solar wind
Tsurutani, B. T.; Goldstein, B. E.; Neugebauer, M. +1 more
A new mechanism for generation of magnetic holes in the solar wind is presented. In the high speed solar wind, large-amplitude right-hand polarized Alfvénic wave packets propagating at large angles to the ambient magnetic field are shown to generate magnetic holes (MHs). Characteristics of these holes crucially depend on plasma β (β being the rati…
A semi-kinetic model of wave-ion interaction in the solar corona
Marsch, E.; Vocks, C.
A semi-kinetic model of the ions in the solar corona is presented, which includes the effects of wave-particle interactions and Coulomb collisions. At the coronal base a spectrum of Alfvén waves is assumed. The spatiotemporal evolution of the spectrum in a 2-D computational domain is determined, taking the absorption of the waves by the particles …
An ICME observed by Voyager 2 at 58 AU and by Ulysses at 5 AU
Wang, C.; Heber, B.; von Steiger, R. +1 more
Between days 175 and 180 (June 24 through 29) of 1999, the PLS instrument on Voyager 2 observed alpha particle enhancements with fractional percentages of alpha to proton number densities exceeding 10%. Ulysses (located at 5.3 AU) observed at least two candidate source features for these enhancements. To identify the correct source structure, a 1D…
Solar cycle variations in the electron heat flux: Ulysses observations
Lin, Naiguo; Gary, S. Peter; Scime, Earl E. +2 more
Solar wind observations by the Ulysses spacecraft now include nearly ten years of continuous ion and electron measurements. In this study, we report detailed measurements of the electron heat flux in the solar wind. In particular, we examine the heat flux measurements for long-term correlations with wave activity and solar wind speed. We find that…
Ion isotropy and ion resonant waves in the solar wind: Cassini observations
Gurnett, Donald A.; Kellogg, Paul J.; Kurth, William S. +1 more
Electric fields in the solar wind, in the range of one Hertz, are reported for the first time from a 3-axis stabilized spacecraft. The measurements are made with the Radio and Plasma Wave System (RPWS) experiment on the Cassini spacecraft [Gurnett et al., 2000]. Kellogg [2000] suggested that such waves could be important in maintaining the near-is…
Waves close to the crossover frequency in the Jovian middle magnetosphere
Dougherty, Michele K.; Petkaki, Panagiota
The presence of heavy ions in a plasma introduces additional characteristic frequencies one of which is a crossover frequency between each adjacent pair of gyrofrequencies of the ions present. The crossover frequency is controlled by the fractional ion charge densities. The phase speed of the L and R wave modes have the same phase velocity at this…
The influence of the Sun's magnetic field on energetic particles at high heliospheric latitudes
Balogh, A.; Forsyth, R. J.; Goldstein, B. E. +5 more
The first passage of the Ulysses spacecraft to high latitudes was during the declining phase of solar cycle 22. The recent second passage to high latitudes was close to the maximum of solar cycle 23. The axis of the dipolar component of the Sun’s magnetic field was close to 90° from the spin axis, and the coronal neutral line extended up to high l…