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Cluster II: Plasma Measurements in Three Dimensions
Escoubet, C. P.; Schmidt, R.
After the dramatic accident of the first Ariane 5 rocket on 4 June 1996, causing the loss of the four European Space Agency's Cluster spacecraft, a recovery programme was initiated. During 10 months, alternative studies and intense negotiations were conducted with industry, and on 3 April 1997, the ESA Science Programme Committee agreed on the re-…
Signatures of Magnetic Reconnection and Observed EUV Emission Line Profiles in An Active Region
Wilhelm, K.; Kjeldseth-Moe, O.; Brekke, P. +2 more
We report on observations with SUMER on SOHO of high-velocity events, also called explosive events. The high spatial and spectral resolutions of SUMER allow simultaneous observations of EUV emission lines formed at different temperatures within the transition region. Complex line profiles with three separate line components appear to be a characte…
Sumer Observations of the Quiet Sun: Transition Region and Low Corona
Wilhelm, Klaus
SUMER - the Solar Ultraviolet Measurements of Emitted Radiation instrument on the Solar and Helio-spheric Observatory (SOHO) of ESA and NASA - observed its first light on January 24, 1996 and covered the minimum of the sunspot activty between the solar cycles 22 and 23 with nearly continuous observations. Consequently, in many studies particular e…
The Sun and the Solar Wind Close to the Sun
Suess, S. T.
One of the benefits of the Ulysses, SOHO, and YOHKOH missions has been a strong stimulus to better understand the magnetohydrodynamic processes involved in coronal expansion. Three topics for which this has been especially true are described here. These are: (i) The observed constancy of the radial interplanetary magnetic field strength (as mapped…
3-D Magnetic Configurations for Filaments and Flares: The Role of ``Magnetic Dips'' and ``Bald Patches''
Vial, J. -C.; van Driel-Gesztelyi, L.; Aulanier, G. +8 more
The 3-D magnetic configuration of a filament and of a low energy flare is reconstructed, using linear mag- netohydrostatic (lmhs) extrapolations. In both cases, we find observational signatures of energy release at the locations of computed ``bald patches'' separatrices, characterised by field lines which are tangent to the photosphere.The filamen…
On the Sources of Jovian Hectometric Radiation
Misawa, H.; Morioka, A.; Nakagawa, F.
Jovian hectometric radiation(HOM) emitted from the polar region of the Jovian magnetsphere reflects the information on the electro-magnetic environment of the source region. Using the Ulysses URAP and SWOOPS data, the occurrence characteristics of HOM and its relation to the solar wind were investigated. As a result, we found that HOM can be class…
Study of CME Structure and Evolution Deduced from Ulysses/Hi-Scale Energetic Particle Observations
Malandraki, O.; Sidiropoulos, N.; Saris, E. T. +1 more
In this work, we study the anisotropy characteristics of solar energetic electron (E > 53 keV) fluxes observed by the ULYSSES/HI-SCALE instrument during the passage of a well-identified Coronal Mass Ejection. On the basis of the energetic electron observations, firm conclusions are drawn on whether the detected Coronal Mass Ejection has been de…
Numerical Simulations of Trapped Slow Magnetosonic Waves in Solar Coronal Plumes
Ofman, L.; Deforest, C. E.
Recent observations of polar plumes in the southern solar coronal hole by the Extreme ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft show signatures of quasi-periodic compressional waves. Here, we present the results of a nonlinear, 2D MHD simulation of the slow magnetosonic waves in plumes for typical coronal conditions consiste…
Solar Prominences Observed by Soho (SUMER, CDS, EIT) and Ground-Based Observatories (GBO)
Heinzel, P.; Schmieder, B.; Rudawy, P. +1 more
We present two sets of prominence observations in higher lines of the hydrogen Lyman series (from Lδ to L-9), together with some other UV lines. These data have been obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard the SOHO satellite in June 1997. Coordinated observations were also taken by other SOHO instruments…
Search for Velocity Variations in Fe XIV 5304 A&ring Coronagraph Observations Near Activity Minimum
Howard, R. A.; Wood, B. E.; Karovska, M. +4 more
The LASCO C1 coronagraph on the SOHO satellite observes the solar corona from 1.1 to 3.0 Ro, and contains a Fabry-Perot interferometer which can image the corona in the 1.8 million K Fe XIV green line. We designed an observing program with reduced spatial coverage and reduced profile coverage at only three wavelengths to study coronal heating in o…