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Recurrence of Energetic Particle Flux Anisotropy as Observed by ERNE on 9 July 1996
Laitinen, T.; Vainio, R.; Valtonen, E. +3 more
A solar energetic particle event was observed on 9 July 1996, by the ERNE sensors LED and HED on board the SOHO spacecraft. The arrival of the first protons in the energy range >20 MeV took place at 09:55 UT, 43 min after the maximum in the X-ray and Hα radiation of a flare located at S10 W30. The rise phase of the particle intensities at all e…
Pole-To Solar Wind Density from ULYSSES Radio Measurements
Issautier, K.; Moncuquet, M.; Meyer-Vernet, N. +1 more
We present new in situ measurements of solar wind electron density as a function of heliolatitude. The data were obtained on Ulysses during its fast transit from south solar pole to north solar pole, at heliocentric distance about 1.5 AU, near the 1996 solar activity minimum. The density is measured accurately using the method of quasi-thermal noi…
Implications of Proton Anisotropy Development Observed by the ERNE Instrument During the 9 July 1996 Solar Particle Event
Laitinen, T.; Vainio, R.; Torsti, J. +1 more
We analysed the solar particle event following the 9 July 1996 solar flare. High-energy protons were detected by the ERNE instrument on board SOHO. Anisotropy of arriving protons revealed very peculiar non-monotonic development. A short period of almost isotropic distribution was imbedded into the prolonged period of beam-like distribution of 14-1…
Impact of Magnetic Environment on the Generation of High-Energy Neutrons at the Sun
Torsti, J.; Usoskin, I. G.; Kocharov, L. G. +3 more
This paper demonstrates the important interplanetary manifestation of strongly tilted magnetic fields at the flare site. We start with analysis of Big Bear Solar Observatory (BBSO) observations of magnetic structures at sites of two flares responsible for >100 MeV neutron events. Based on these observations, a model of neutron production is con…
First Observations of Coronal Hole Structure and Evolution Using Soho-Cds
Harrison, R. A.; Moore, V.; Insley, J. E.
We report on initial observations of coronal holestructure and evolution by the Coronal Diagnostic Spectrometer (CDS) instrument on board the Solar and Heliospheric Observatory (SOHO). The data show that there is coronal activity on time scales of tens of minutes, manifested as brightenings at chromospheric network cell junctions in extreme ultrav…
Anomalous Cosmic-Ray Helium, Nitrogen and Oxygen in 1996 - Measurements of the ERNE Instrument on-board SOHO
Vainio, R.; Valtonen, E.; Riihonen, E. +4 more
The energy spectra of the anomalous components of helium, nitrogen and oxygen have been measured by the ERNE experiment on board the SOHO spacecraft. During February 28-April 30, 1996, the maximum intensity of anomalous helium was found to be 3.8 × 10-5 cm-2 sr-1 s-1 (MeV nucl-1)-1 …
M VIII Diagnostic Line Ratios in SKYLAB Solar Observations
Doyle, J. G.; Keenan, F. P.; Widing, K. G. +4 more
Recent calculations of Mgviii electron and proton impact excitations rates are used to derive theoretical electron temperature (Te)- and density (Ne)-sensitive emission line ratios involving transitions in the 315-782 Å wavelength range. Some of these ratios are presented in the form of ratio-ratio diagrams, which should in p…
First Energetic Particle Events Observed by the ERNE Instrument
Laitinen, T.; Vainio, R.; Valtonen, E. +6 more
The energetic particle instrument ERNE on-board SOHO started its observations on December 15, 1995. The low-energy sensor of ERNE, LED, is capable of measuring particles in the energy range from 1 to 10 MeV nucl-1. From the beginning of the year 1996 until May 22, 1996, LED-observations included four energetic particle events above thre…
Study of Coronal Transients in UV Line Emission
Noci, Giancarlo; Martin, Renato; Maccari, Lisa
We investigate the expected emission from coronal transients in the following spectral lines observable with the Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO: Hi Lα 1216 Å, Ovi 1032-1037 Å, Nv 1239-1243 Å, Mgx 610-625 Å, Sixii 499-521 Å, and Fexii 1242 Å. We calculate line intensities and profiles for typical CME conditions, and we an…
Solar and heliospheric plasma physics. Proceedings. 8th European Solar Physics Meeting, Halkidiki (Greece), 13 - 18 May 1996.
Heinzel, P.; Simnett, G.
The main topic was the interaction of the Sun with the heliosphere, focused on first results from SOHO and new results from Ulysses. The following topics were dealt with: solar dynamos, solar shape, convection zone, solar pulsations, solar activity, solar atmosphere, solar corona, solar spectra, solar prominences, solar flares, UV spectra, solar w…