Search Publications

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…

Correction to “Ion isotropy and ion resonant waves in the solar wind: Cassini observations”

Gurnett, Donald A.; Kellogg, Paul J.; Kurth, William S. +1 more

Interplanetary acceleration of coronal mass ejections

St. Cyr, O. C.; Kaiser, M. L.; Gopalswamy, N. +3 more

Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an “effective” acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed na…

Coronal dimmings and energetic CMEs in April-May 1998

Thompson, B. J.; Delaboudinière, J. -P.; Nitta, N. +2 more

We have analyzed the coronal dimmings for seven fast (> 600 km/s) coronal mass ejections (CMEs) occurring between 23 April and 9 May which were associated with flares from NOAA active region (AR) 8210. Each of these CMEs had at least one group of interplanetary radio bursts associated with them. These dimming regions were identified by their st…