Search Publications
UV spectroscopy with SOHO
Brekke, P.; Harra, L. K.
The UV spectroscopy from SOHO has provided new and exciting results from a wide range of phenomena observed on the Sun. Determination of plasma parameters such as velocity, density, temperatures, line widths and abundances have provided new physical insight into fundamental problems in solar physics. These include magnetic reconnection, quiet Sun …
UV and EUV observations of stellar coronal structure and activity
Brown, Alexander
Ultraviolet (HST, FUSE) and extreme-ultraviolet (EUVE) observations of stellar coronae and flare-related activity are reviewed, with particular attention being devoted to the coronas information that is obtainable in the ultraviolet but not from the X-ray region. The coronas temperature, density, and emission measure distributions of active stars …
Energetic H/He intensity ratio under solar maximum and solar minimum conditions: Ulysses observations
Lario, D.; Roelof, E. C.; Maclennan, C. G. +3 more
We study the solar cycle variability of the heliospheric energetic proton-to-helium abundance ratios. We use 0.5-1.0 MeV nucleon -1 proton and helium intensities observed by the Ulysses spacecraft at both high and low heliographic latitudes. Ulysses observations show that during solar maximum the 0.5-1.0 MeV nucleon -1H/He in…
Solar eruptions and long wavelength radio bursts: The 1997 May 12 event
Kaiser, M. L.; Gopalswamy, N.
We report on the cause of the 1997 May 12 type II bursts observed by ground based and space-based radio instruments. We estimate the fast mode speed in the corona as a function of heliocentric distance to identify the regions where fast mode shocks can be driven by CMEs. We find that both the coronal and the interplanetary type II bursts can be ex…
Laboratory calibration of the cassini cosmic dust analyser (CDA) using new, low density projectiles
Srama, R.; Grün, E.; Müller, M. +9 more
The Cassini Cosmic Dust Analyser (CDA), developed from the Galileo and Ulysses dust instruments with the addition of a Chemical Analyser, is currently travelling outward from the Earth (collecting data from March 1999 onward) to the Saturnian system (arrival 2004) via Jupiter. The Chemical Analyser will provide information on the elemental composi…
Modeling the radial variation of coronal streamer belts during sunspot ascending phase
Hoeksema, J. T.; Zhao, X. P.; Rich, N. B.
The coronal streamer belts and their radial variation between 2.5 and 20.0 solar radii in the ascending phase of the solar cycle can be well reproduced using the horizontal current-current sheet-source surface magnetic field model with the set of model parameters determined based on MDI and LASCO Carrington maps during 1996 minimum activity phase.
Total solar irradiance variations since 1978
Fröhlich, Claus
A composite record of solar total irradiance compiled from measurements made by five independent space-based radiometers since 1978 is the basis for an evaluation of the influence of solar activity on total solar irradiance. An empirical model that parameterizes the combined influences of dark sunspots and bright faculae features on solar irradian…
Relationships between CME's and prominences
van Driel-Gesztelyi, L.; Aulanier, G.; Schmieder, B. +6 more
We have studied the erupting prominences which were associated with coronal mass ejections during a series of campaigns involving both spacecraft and ground-based observatories. The evolution of the physical conditions within the prominences was established from Hα and magnetic field observations. Particular attention ahs been paid to the presence…
New insights on the onsets of coronal mass ejections from soho
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +6 more
Coronal mass ejections (CMES) are among the most dramatic forms of transient activity occurring in the solar atmosphere. Despite over twenty years of research, many basic questions related to the physics of CMEs have remained unanswered. Observations with the LASCO and EIT experiments on SOHO, combined with recent theoretical modeling, have provid…
The composition of the solar wind
Wimmer-Schweingruber, Robert F.
Accurate knowledge of the composition of the solar wind and of solar system abundances allows us to improve our understanding about various processes affecting the elemental, isotopic, and charge-state abundances of the solar wind. During the evolution of the Sun, isotopic and elemental abundances have been affected by migration processes at the i…