Search Publications
MHD Interpretation of LASCO Observations of a Coronal Mass Ejection as a Disconnected Magnetic Structure
Llebaria, A.; Michels, D. J.; Koomen, M. J. +15 more
We present a qualitative and quantitative comparison of a single coronal mass ejection (CME) as observed by LASCO (July 28-29, 1996) with the results of a three-dimensional axisymmetric time-dependent magnetohydrodynamic model of a flux rope interacting with a helmet streamer. The particular CME considered was selected based on the appearance of a…
EUV Observations of a Macrospicule: Evidence for Solar Wind Acceleration?
Harrison, R. A.; Pike, C. D.
We present a unique observation of a macrospicule, recorded in extreme ultraviolet light on 11 April 1996, using the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The observation was made by chance as part of a daily, large-area mapping sequence. Although the feature has some characteristics of the c…
LASCO Observations of Disconnected Magnetic Structures Out to Beyond 28 Solar Radii During Coronal Mass Ejections
Llebaria, A.; St. Cyr, O. C.; Plunkett, S. P. +16 more
Two coronal mass ejections have been well observed by the LASCO coronagraphs to move out into the interplanetary medium as disconnected plasmoids. The first, on July 28, 1996, left the Sun above the west limb around 18:00 UT. As it moved out, a bright V-shaped structure was visible in the C2 coronagraph which moved into the field-of-view of C3 and…
The Relationship of Green-Line Transients to White-Light Coronal Mass Ejections
Llebaria, A.; St. Cyr, O. C.; Plunkett, S. P. +18 more
We report observations by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft of three coronal green-line transients that could be clearly associated with coronal mass ejections (CMEs) detected in Thomson-scattered white light. Two of these events, with speeds >25 km s-1, may be classified as `whip-like' transien…
In-Flight Performance of the Virgo Luminosity Oscillations Imager Aboard SOHO
Appourchaux, Thierry; Andersen, Bo N.; Fröhlich, Claus +3 more
The Luminosity Oscillations Imager (LOI) is a part of the VIRGO instrument aboard the Solar and Heliospheric Observatory (SOHO). The scientific objective of the LOI experiment is to identify and characterize pressure and internal gravity oscillations of the Sun by observing the radiance variations. The LOI is a low-resolution imager with 12 pixels…
Modeling the distribution of magnetic fluxes in field concentrations in a solar active region
Shine, Richard A.; Title, Alan M.; Schrijver, Carolus J. +1 more
Much of the magnetic field in solar and stellar photospheres is arranged into clusters of `flux tubes', i.e., clustered into compact areas in which the intrinsic field strength is approximately a kilogauss. The flux concentrations are constantly evolving as they merge with or annihilate against other concentrations, or fragment into smaller concen…
Eruptive prominence and associated CME observed with SUMER, CDS and LASCO (SOHO)
Schmieder, B.; Brekke, P.; Kucera, T. +3 more
Observations of an eruptive prominence were obtained on 1 May 1996, with the SUMER and CDS instruments aboard SOHO during the preparatory phase of the Joint Observing Programme JOP12. A coronal mass ejection observed with LASCO is associated temporally and spatially with this prominence. The main objective of JOP12 is to study the dynamics of prom…
Soho Cds nis in-flight intensity calibration using a plasma diagnostic method
Mason, H. E.; Landini, M.; Landi, E. +1 more
The internal intensity calibration of the Coronal Diagnostic Spectrometer (CDS) - Normal Incidence Spectrometer (NIS) is studied using the Arcetri diagnostic method. A large number of spectral lines observed by the CDS-NIS 1 and NIS 2 windows in a solar active region is analysed in order to determine the intensity calibration curve for both channe…
The relationship between UV and X-ray active region structures
Matthews, S. A.; Harra-Murnion, L. K.
Yohkoh and the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) jointly observed two brightenings in active region NOAA 7981 on 6 August 1996. Combining the UV data from CDS with information from the high time resolution coronal images obtained with the Soft X-ray Telescope (SXT) on Yohkoh, provides us with im…
The Directivity of Solar Kilometric Type III Bursts: Ulysses-Artemis Observations in and Out of the Ecliptic Plane
Bougeret, J. -L.; Hoang, S.; Poquérusse, M.
Comparing the records of the radio spectrographs ARTEMIS (100-500 MHz) on the ground and URAP (1-1000 kHz) on the Ulysses spacecraft, we find that most type III bursts extend from the corona to the solar wind. Using the positions of the associated flares, and assuming an average intensity ratio between these two frequency ranges, we derive for the…