Search Publications
Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
Cranmer, Steven R.; van Ballegooijen, Adriaan A.; Edgar, Richard J.
We present a series of models for the plasma properties along open magnetic flux tubes rooted in solar coronal holes, streamers, and active regions. These models represent the first self-consistent solutions that combine (1) chromospheric heating driven by an empirically guided acoustic wave spectrum; (2) coronal heating from Alfvén waves that hav…
Observation of Inertial Energy Cascade in Interplanetary Space Plasma
Bavassano, B.; Pietropaolo, E.; Bruno, R. +6 more
Direct evidence for the presence of an inertial energy cascade, the most characteristic signature of hydromagnetic turbulence (MHD), is observed in the solar wind by the Ulysses spacecraft. After a brief rederivation of the equivalent of Yaglom’s law for MHD turbulence, a linear relation is indeed observed for the scaling of mixed third-order stru…
Evolution of the solar wind proton temperature anisotropy from 0.3 to 2.5 AU
Maksimovic, Milan; Landi, Simone; Hellinger, Petr +5 more
We report an analysis of the proton temperature anisotropy evolution from 0.3 to 2.5 AU based on the Helios and Ulysses observations. With increasing distance the fast wind data show a path in the parameter space (β $\parallel$ p , T $\perp$ p /T $\parallel$ p ). The first part of the trajectory is well describe…
A New View of the Coupling of the Sun and the Heliosphere
Zurbuchen, Thomas H.
The structure of the global heliospheric field reflects the physical properties of the low corona. The implied connections between solar and heliospheric evolution have been analyzed by a powerful multisatellite solar and heliospheric observatory that includes the Ulysses and the Solar and Heliospheric Observatory (SOHO) spacecraft. This coordinat…
Evidence of Superdiffusive Transport of Electrons Accelerated at Interplanetary Shocks
Perri, S.; Zimbardo, G.
We study the transport properties of energetic electrons accelerated at corotating interaction regions in the solar wind considering the possibility of anomalous diffusion. It is shown that the particle time decay has a power-law behavior when a non-Gaussian propagator, appropriate for superdiffusive transport, is assumed for particles accelerated…
A Floor in the Solar Wind Magnetic Field
Cliver, E. W.; Svalgaard, L.
Long-term (~130 years) reconstruction of the interplanetary magnetic field (IMF) based on geomagnetic indices indicates that the solar wind magnetic field strength has a ``floor,'' a baseline value in annual averages that it approaches at each 11 yr solar minimum. In the ecliptic plane at 1 AU, the IMF floor is ~4.6 nT, a value substantiated by di…
The Composition of the Solar Wind in Polar Coronal Holes
Gloeckler, George; Geiss, Johannes
The solar wind charge state and elemental compositions have been measured with the Solar Wind Ion Composition Spectrometers (SWICS) on Ulysses and ACE for a combined period of about 25 years. This most extensive data set includes all varieties of solar wind flows and extends over more than one solar cycle. With SWICS the abundances of all charge s…
Multi-Spacecraft Study of the 21 January 2005 ICME. Evidence of Current Sheet Substructure Near the Periphery of a Strongly Expanding, Fast Magnetic Cloud
Dandouras, I.; Fazakerley, A. N.; Crooker, N. U. +6 more
We examine the near-Earth Interplanetary Coronal Mass Ejection (ICME) apparently related to the intense Solar Energetic Particle (SEP) event of 20 January 2005. Our purpose is to contribute to the understanding of the macroscopic structure, evolution and dynamics of the solar corona and heliosphere. Using Cluster, ACE and Wind data in the solar wi…
Interstellar Dust in the Solar System
Altobelli, Nicolas; Krüger, Harald; Grün, Eberhard +1 more
The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse almost perpendicular to the ecliptic plane (inclination 79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. The in situ dust detector on board continuously measured interstellar dust grains with masses up to 10-13 k…
Density and Magnetic Field Signatures of Interplanetary 1/f Noise
Romoli, M.; Bemporad, A.; Poletto, G. +4 more
We investigate the occurrence of 1/f noise in the interplanetary density and the magnetic field at varying heliocentric latitudes. The characteristic spectral amplitudes can be found in Ulysses density and magnetic data in the expected frequency ranges at all available latitudes, ranging from the ecliptic plane to more than 80°. Average spectra in…