Search Publications
Search for a chromospheric resonator above sunspots
Kjeldseth-Moe, O.; Brekke, P.; Brynildsen, N. +2 more
We have recently observed thirteen sunspots, both with CDS on SOHO and TRACE. For each sunspot we investigate the oscillations in the chromosphere, transition region and corona. Above the umbra the power spectra show one dominant peak corresponding to a period of 3 minutes. The intensity oscillation amplitude increases with increasing temperature,…
Flare characteristics: Properties of eruptive and non-eruptive events and their associations
Culhane, J. L.; Harra, L. K.; Kay, H. R. M. +1 more
The complex: relationship between solar flares and coronal mass ejections is investigated using a comparison of flare parameters for a total of 69 ejective and non-ejective flares. In the case of solar flares which do not show mass ejection there seems to be a clear relationship between the peak intensity and duration, with higher intensity events…
On the sudden disappearances of solar filaments and their relationship with coronal mass ejections
Pojoga, S.; Huang, T. S.
Sudden disappearances of prominences/filaments were identified from the Prairie View Solar Observatory H α imagesand Meudon Observatory spectroheliograms for the period January 1, 2000 to March 31, 2000. Three classes of disappearances were considered for the purpose of this study: eruptive, quasi-eruptive and vanishing filaments. The H α events w…
Advances in magnetospheric radio wave analysis and tomography
Gurnett, D. A.; Escoubet, C. P.; Pickett, J. S. +7 more
Initial theoretical studies of multi-spacecraft radio tomographic imaging of the magnetosphere have shown the potential scientific value of the technique. We report a series of multistatic radio propagation experiments with the goal of testing and verifying the capabilities of radio tomography. These experiments focused specifically on measuring t…
Modeling solar and stellar flares
Reale, F.
The thermal phase of solar X-ray flares has been described as heating-triggered evolution of plasma confined in coronal loops. This paper describes how the modeling of the thermal phase of spatially resolved solar X-ray flares has been extended to investigate spatially unresolved stellar X-ray flares with different scopes, aims and perspectives. H…
Transport of a few-MEV jovian and galactic electrons at solar maximum
Ferreira, S. E. S.; Potgieter, M. S.; Heber, B. +2 more
The heliospheric modulation of galactic and jovian electrons is studied using a three-dimensional, steady-state model based on Parker's transport equation including the jovian source. The model is developed to study both jovian and galactic electrons. It is illustrated how the electron intensity-time profile along the Ulysses trajectory is effecte…
Distinct shock acceleration processes — Evaluation of the magnetic trap dimensions formed upstream of an interplanetary shock using measurements of the ulysses spacecraft
Sarris, E. T.; Anagnostopoulos, G. C.; Marhavilas, P. K. +1 more
We analyze the acceleration signatures of energetic ions (E > 50 keV) and electrons (E > 30 keV) being observed on day 256 of the year 1992 UT, in the vicinity of the surface of a fast-mode quasi-perpendicular interplanetary hydromagnetic shock, using fine time resolution measurements by the HI-SCALE instrument onboard the Ulysses spacecraft…
How directions and helicity of erupted solar magnetic fields define geoeffectiveness of coronal mass ejections
Wang, Haimin; Yurchyshyn, Vasyl; Abramenko, Valentyna
In this study we report on the relationship between the projected speed of CMEs, measured at 20R from SOHO/LASCO images, and the hourly averaged magnitude of the southwardly directed magnetic field, B z, at the leading edge of interplanetary ejecta, as measured by the ACE magnetometer. We found that those CMEs that originate at the cent…
Heliospheric Langmuir wave observations from the Ulysses spacecraft
McComas, D. J.; Lin, Naiguo; MacDowall, R. J.
Langmuir waves are electrostatic plasma oscillations produced by unstable electron beams in the solar wind and elsewhere. Typical electron sources are solar flares, shocks, and magnetic holes. In this paper, we present an overview of the Langmuir waves observed by Ulysses during both its solar minimum and solar maximum orbits. Langmuir waves in ma…
The metallicity of β Cephei stars on the basis of the satellite ultraviolet spectra
Niemczura, E.; Cugier, H.; Daszyńska, J.
We derive the mean stellar parameters like angular diameter, effective temperature, and metallicity from ultraviolet spectra for all β Cephei stars observed during the IUE satellite mission, including those belonging to the three open clusters. For this purpose we fit the theoretical flux distributions of Kurucz's models to observed low-resolution…