Search Publications
Corotating interaction regions
Heber, B.; Zhang, M.; Sanderson, T. R.
Corotating Interaction Regions are long lasting large-scale plasma structures generated in low and middle latitude regions of the heliosphere by the interaction of a stable fast solar wind stream with the surrounding slow solar wind. Associated with these plasma structures are recurrent MeV-ion events and recurrent decreases of the galactic and an…
Variations in total solar and spectral irradiance as measured by the VIRGO experiment on SOHO
Fröhlich, Claus; Wehrli, Christoph; Pap, Judit +3 more
The Variability IRradiance Gravity Oscillation (VIRGO) experiment on SOHO has been observing total solar and spectral irradiances at 402 nm (blue channel), 500 nm (green channel), and 862 nm (red channel) since January 1996. The VIRGO observations have shown that solar active regions influence both total and spectral irradiances in a similar fashi…
On the gradients of ACR oxygen at intermediate heliocentric distances: Ulysses/Soho results
Torsti, J.; Sanderson, T. R.; Marsden, R. G. +3 more
During 1997 and up to the present time, the heliocentric position of the Ulysses spacecraft has changed only slowly in distance and latitude, being close to the equator at a distance of ~5 AU. This period provides an excellent opportunity to observe the evolution of the Anomalous Cosmic Ray (ACR) spectrum at a location intermediate between 1 AU an…
Implications of the heliospheric modulation of cosmic ray electrons observed by ulysses
Ferreira, S. E. S.; Potgieter, M. S.; Heber, B. +2 more
The results of a moderate drift model with anisotropic perpendicular diffusion for the heliospheric modulation of galactic cosmic rays were compared with electron spectra observed by the Kiel Electron Telescope on board the Ulysses spacecraft for four distinctive periods, 1992, 1995, 1996, and 1997, respectively, for relative large solar activity …
Latitudinal and radial variation of >2 GeV/n protons and α-particles in the northern heliosphere: ulysses cospin/ket and neutron monitor network observations
Kunow, H.; Bothmer, V.; Wibberenz, G. +10 more
Ulysses, launched in October 1990, crossed in December 1997 the heliographic equator and completed its first out of ecliptic orbit. During the time period from February 1995 to November 1997 solar activity was low and the spacecraft scanned the latitude range from 80° N to the heliographic equator. The Kiel Electron Telescope on-board Ulysses meas…
The Cassini-Huygens ACP experiment and exobiological implications
Israel, G.; Coll, P.; Raulin, F. +3 more
Since the discovery of its dense nitrogen atmosphere Titan, the largest satellite of Saturn has always been the subject of a strong interest by the scientific community of the exobiologists. The main reason is that Titan's atmosphere is believed to be over geologic time a permanent source of N- containing organic molecules (mostly nitriles) and of…
The role of stars in the energetics of LINERs
Maoz, Dan
Imaging studies have shown that ~ 25% of LINER galaxies display a compact nuclear UV source. I compare the HST ultraviolet (1150-3200 Å) spectra that are now available for seven such ``UV-bright'' LINERs. The spectra of NGC 404, NGC 4569, and NGC 5055 show clear absorption-line signatures of massive stars, indicating a stellar origin for the UV co…
Time-distance helioseismology
Kosovichev, A. G.; Scherrer, P. H.; Duvall, T. L.
The time-distance helioseismology (or helioseismic tomography) is a new promising method for probing 3-D structures and flows beneath the solar surface, which is potentially important for studying the birth of active regions in the sun's interior and for understanding the relation between the internal dynamics of active regions and chromospheric a…
Solar irradiances of UV and EUV lines during the minimum of the sunspot activity in 1996
Wilhelm, K.; Curdt, W.; Schühle, U. +6 more
Full Sun observations in UV and EUV emission lines were performed by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric preflight calibration of SUMER is traceable to a primary radiometric source standard - the electron storage ring BESSY. Based on this calibration and …
Results from the GOLF instrument on SOHO
Baudin, F.; García, R. A.; Pallé, P. L. +9 more
An 800 day series of GOLF velocity data, with uniquely high continuity and stability, offers the best ever signal to noise ratio obtained in global Sun observations. Following meticulous efforts to provide reliable calibration, these data have been used for measurements of frequencies, line-widths and power in the p-modes, which are used for inver…