Search Publications
Formation and Evolution of Corotating Interaction Regions and their Three Dimensional Structure
Gosling, J. T.; Pizzo, V. J.
Corotating interaction regions are a consequence of spatial variability in the coronal expansion and solar rotation, which cause solar wind flows of different speeds to become radially aligned. Compressive interaction regions are produced where high-speed wind runs into slower plasma ahead. When the flow pattern emanating from the Sun is roughly t…
CIR Morphology, Turbulence, Discontinuities, and Energetic Particles
Tsurutani, B. T.; Lucek, E.; Crooker, N. U. +18 more
Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses how they can vary from case to case and with distance from the Sun and possible causes of those va…
The Solar Origin of Corotating Interaction Regions and Their Formation in the Inner Heliosphere
Bochsler, P.; Balogh, A.; Lucek, E. +20 more
Corotating Interaction Regions (CIRs) form as a consequence of the compression of the solar wind at the interface between fast speed streams and slow streams. Dynamic interaction of solar wind streams is a general feature of the heliospheric medium; when the sources of the solar wind streams are relatively stable, the interaction regions form a pa…
Comet Halley's Gas Composition and Extended Sources: Results from the Neutral Mass Spectrometer on Giotto
Eberhardt, Peter
The Neutral Mass Spectrometer on the Giotto spacecraft established that H2O is the dominant species in Comet Halley's volatiles and determined the abundance of more than 10 parent species. The instrument discovered strong extended H2CO and CO sources in the coma of Comet Halley. Polymerized H2CO associated with the…
Solar Origin and Interplanetary Evolution of Stream Interfaces
Forsyth, R. J.; Marsch, E.
In a Corotating Interaction Region (CIR) the stream interface is identified as a relatively sharp density drop, temperature rise, and flow shear in the solar wind, and is now generally believed to mark the boundary between solar wind which was originally slow when it left the Sun and solar wind which was originally fast. This paper summarises some…
Solar Wind Models from the Sun to 1 AU: Constraints by in Situ and Remote Sensing Measurements
Marsch, E.
There are three major types of solar wind: The steady fast wind originating on open magnetic field lines in coronal holes, the unsteady slow wind coming probably from the temporarily open streamer belt and the transient wind in the form of large coronal mass ejections. The majority of the models is concerned with the fast wind, which is, at least …
Composition Variations in the Solar Corona and Solar Wind
Raymond, J. C.
Order of magnitude variations in relative elemental abundances are observed in the solar corona and solar wind. The instruments aboard SOHO make it possible to explore these variations in detail to determine whether they arise near the solar surface or higher in the corona. A substantial enhancement of low First Ionization Potential (FIP) elements…
CIR Associated Energetic Particles in the Inner and Middle Heliosphere
Mason, G. M.; Sanderson, T. R.
Energetic particles associated with Corotating Interaction Regions (CIRs) are observed throughout the inner and middle heliosphere, showing large positive (>100%/AU) radial intensity gradients. Their appearance at 1 AU is associated with the appearance of fast, recurrent solar wind streams. At several AU, CIR energetic particles are accelerated…
Origin, Injection, and Acceleration of CIR Particles: Observations Report of Working Group 6
Fränz, M.; Simnett, G. M.; Klecker, B. +18 more
This report emphasizes new observational aspects of CIR ions revealed by advanced instruments launched on the Ulysses, WIND, SOHO, and ACE spacecraft, and by the unique vantage point of Ulysses which carried out the first survey of Corotating Interaction Region (CIR) properties over a very wide range of heliolatitudes. With this more complete obse…
Polarization of Light Scattered by Cometary Dust Particles: Observations and Tentative Interpretations
Levasseur-Regourd, A. -Chantal
Analysis of the polarization of light scattered by cometary particles reveals similarities amongst the phase curves, together with some clear differences: i) comets with a strong silicate emission feature present a high maximum in polarization, ii) the polarization is always slightly lower than the average in inner comae and stronger in jet-like s…