Search Publications
SUMER observations of Doppler shift in the quiet Sun and in an active region
Doyle, J. G.; Teriaca, L.; Banerjee, D.
The UV spectral lines formed at transition region temperatures in the solar atmosphere, show a prevailing redshifted emission. Using the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft, we measure the amount of line shift as a function of the temperature for several spectr…
The NE BT VIII (lambda 770) resonance line: solar wavelengths determined by SUMER on SOHO
Wilhelm, K.; Curdt, W.; Dammasch, I. E. +1 more
The investigation of the source and acceleration of the solar wind was among the prime scientific goals of SOHO - ESA's and NASA's Solar and Heliospheric Observatory. For the coronal regions closest to the Sun, the bright extreme ultraviolet (EUV) resonance lines of the Ne viii spectrum at 770 { Angstroms} and 780 { Angstroms} with a formation tem…
Coronal hole diagnostics out to 8Rsun
Doyle, J. G.; Teriaca, L.; Banerjee, D.
The Si viii line width measurements and N_e estimates based on SUMER observations are combined with LASCO and UVCS output to provide an overview of its variations with height above a polar coronal hole. From the combined dataset we find a radial dependence of the electron density, in the range 1-2 Rsun as r(-8) , from 2 to 4 Rsun
3-D magnetic configurations supporting prominences. III. Evolution of fine structures observed in a filament channel
van Driel-Gesztelyi, L.; Aulanier, G.; Schmieder, B. +3 more
On September 25() th 1996, a quiescent filament located near the center disc (S2, E5) was observed on the German VTT (Tenerife) with the MSDP instrument, in the Hα line center and wings. SOHO/MDI line-of-sight magnetograms were co-aligned with the MSDP images, showing the position and evolution of the lateral feet of the filament in the vicinity o…
Self-consistent Alfvén-wave transmission and test-particle acceleration at parallel shocks
Vainio, R.; Schlickeiser, R.
The transmission of Alfvén waves at parallel shocks is treated self-consistently, i.e., taking the pressure and energy flux exerted by the waves into account when determining the shock's gas compression ratio. The resulting test-particle acceleration and transport parameters at the shock are shown to be functions of five parameters: the Alfvénic M…
A study of extreme ultraviolet blinker activity
Harrison, R. A.; Innes, D. E.; Brooks, D. H. +1 more
In a previous paper (Harrison, 1997a), we reported on the existence of extreme ultraviolet (EUV) flashes, known as blinkers, which were identified in the quiet Sun network using the CDS instrument on board the Solar and Heliospheric Observatory. Since then a number of dedicated observations have been made and we report here on an analysis of 97 bl…
Heliospheric interstellar H temperature from SOHO/SWAN H cell data
Schmidt, W.; Bertaux, J. -L.; Lallement, R. +3 more
We show a first comparison between selected SOHO/SWAN H cell data recorded in 1996-1997 and a simple classical ``hot model'' of the interstellar (IS) H flow in the inner heliosphere. Our goal is to obtain some constraints on the interplanetary background Ly-alpha profiles, for the first time without any assumption on the H cell characteristics. Fo…
The quiet Sun extreme ultraviolet spectrum observed in normal incidence by the SOHO coronal diagnostic spectrometer
Harrison, R. A.; Landini, M.; Innes, D. E. +10 more
The extreme ultraviolet quiet Sun spectrum, observed at normal incidence by the Coronal Diagnostic Spectrometer on the SOHO spacecraft, is presented. The spectrum covers the wavelength ranges 308-381 Ä and 513-633 Ä and is based on data recorded at various positions on the solar disk between October 1996 and February 1997. Datasets at twelve of th…
Temperature and density in a polar plume - measurements from CDS/SOHO
Young, P. R.; Mason, H. E.; Klimchuk, J. A.
A detailed analysis of a particularly intense polar plume observed on the 25th of October, 1996, by the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO) is presented. Above the limb, emission measure distributions derived for both the plume and a section of coronal hole background are found to be sharply…
Heating events in the quiet solar corona: multiwavelength correlations
Krucker, Säm; Benz, Arnold O.
Coronal, transition region and chromospheric lines and centimeter radio emission of the quiet Sun have been simultaneously observed by SoHO and the VLA. The corona above the magnetic network has a higher pressure and is more variable than above the interior of supergranular cells. The Fourier transform in time is found to have steeper spectra in t…