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Observation of Injection and Pre-Acceleration Processes in the Slow Solar Wind
Gloeckler, George
Knowledge of injection and pre-acceleration mechanisms of ions is of fundamental importance for understanding particle acceleration that takes place in various astrophysical settings. The heliosphere offers the best chance to study these poorly understood processes experimentally. We examine ion injection and pre-acceleration using measurements of…
Mechanisms for Latitudinal Transport of Energetic Particles in the Heliosphere
Fisk, L. A.; Jokipii, J. R.
Energetic particles in the heliosphere, from relatively low-energy particles which are accelerated in Corotating Interaction Regions (CIRs) to galactic cosmic rays, are observed to propagate relatively easily in heliographic latitude. Two mechanisms for this transport appear possible: cross-field diffusion, or, in a recent model for the heliospher…
Composition of the Volatile Material in Halley's Coma from In Situ Measurements
Altwegg, K.; Balsiger, H.; Geiss, J.
The investigation of the volatile material in the coma of comets is a key to understanding the origin of cometary material, the physical and chemical conditions in the early solar system, the process of comet formation, and the changes that comets have undergone during the last 4.6 billion years. So far, in situ investigations of the volatile cons…
Swan Observations of the Solar Wind Latitude Distribution and its Evolution Since Launch
Bertaux, Jean-Loup; Lallement, Rosine; Schmidt, Walter +5 more
SWAN is the first space instrument dedicated to the monitoring of the latitude distribution of the solar wind by the Lyman alpha method. The distribution of interstellar H atoms in the solar system is determined by their destruction during ionization charge-exchange with solar wind protons. Maps of sky Ly-α emission have been recorded regularly si…
Modulation of Cosmic Rays and Anomalous Components by CIRs
Potgieter, M. S.; Richardson, I. G.; Heber, B. +6 more
CIRs produce clearly visible recurrent modulation in the intensity of cosmic rays and anomalous components, but are not principally responsible for determining the overall global level of modulation. However, the localized variations imposed by CIRs in the parameters for propagation of energetic particles through the solar wind provide useful diag…
Coronal Hole Boundaries and their Interactions with Adjacent Regions
Schwadron, N. A.; Zurbuchen, T. H.; Fisk, L. A.
Coronal hole boundaries are the interfaces between regions where the coronal magnetic field contains a significant component which is open into the heliosphere and regions where the field is primarily closed. It is pointed out that there are constraints on the magnetic field which opens into the heliosphere that must be satisfied in the corona: it…
EUV Observations Above Polar Coronal Holes
Del Zanna, G.; Fludra, A.; Bromage, B. J. I.
We derive electron temperature and density as a function of height up to 0.2 R⊙ above the limb in polar coronal holes, using five EUV data sets recorded by the SOHO Coronal Diagnostic Spectrometer between July 1997 and February 1998. Radial T and N distributions, averaged in a 2° to 10° range of position angles, are the same above the N…
Development and Effects of Turbulence in Connection with CIRs
Horbury, T. S.; Schmidt, J. M.
We present an overview of the properties of magnetohydrodynamic turbulence within corotating interaction regions (CIRs) and its effects on energetic particles. We stress the importance of both the population of fluctuations in the inner heliosphere and the changing local environment in determining their properties at larger heliospheric distances.…
Search for Signatures of a Coronal Hole in Transition Region Lines Near Disk Center
Bocchialini, K.; Wilhelm, K.; Lemaire, P. +2 more
The analysis of data taken by SUMER near disk center, where a small coronal hole is observed in EIT images, is performed. From the measurements of Doppler non-thermal velocities and intensities, we search for the diagnostics and the signature of small scale structures in the coronal hole using transition region lines. Transition region lines in th…
Acceleration Profile of the Slow Solar Wind as Inferred from Gradual Mass Ejections Observed by LASCO
Stenborg, Guillermo; Srivastava, Nandita; Inhester, Bernd +2 more
The slow solar wind (< 400 km s-1) appears to initiate from the regions in the corona where magnetic fields are closed, or from the interface between streamers and other coronal regions. The nature of the acceleration of slow solar wind is not yet well known. LASCO observations of gradually evolving mass ejections offer us a good opp…