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First Solar EUV Irradiances Obtained from SOHO by the CELIAS/SEM
Wurz, P.; Klecker, B.; Möbius, E. +10 more
The first results obtained with the Solar EUV Monitor (SEM), part of the Charge, Element, and Isotope Analysis System (CELIAS) instrument, aboard the SOlar and Heliospheric Observatory (SOHO) satellite are presented. The instrument monitors the full-disk absolute value of the solar Heii irradiance at 30.4 nm, and the full-disk absolute solar irrad…
Rotating Transition Region Features Observed with the SOHO Coronal Diagnostic Spectrometer
Mason, H. E.; Pike, C. D.
Strong evidence has been found from SOHO-CDS (Solar and Heliospheric Observatory - Coronal Diagnostic Spectrometer) observations to support the hypothesis that rotation plays a major role in the dynamics of transition region features. A comprehensive survey of the CDS daily synoptic rasters has been carried out to select dynamic events by searchin…
EUV97: Improvements to EUV Irradiance Modeling in the Soft X-Rays and FUV
Tobiska, W. Kent; Eparvier, F. G.
EUV97 is a solar EUV empirical model that incorporates revised soft X-ray fluxes from the SOLRAD-11 satellite (1976-1979) and uses Lα recently recalibrated to the UARS satellite (1991-present) SOLSTICE Lα. The soft X-ray data have been revised from the original flux values using Mewe's spectral fits to the data. The recalibrated AE-E and SME Lα da…
Time Variability of Active Region Loops Observed with the Coronal Diagnostic Spectrometer (Cds) on SOHO
Kjeldseth-Moe, O.; Brekke, P.
Monochromatic images from the Coronal Diagnostic Spectrometer (CDS) of loops above active regions show clear evidence of rapid time variability. The rapidly changing conditions that we observe give a new conception of loop systems that has never before been seriously considered. Loop systems, particularly in emission lines formed at temperatures i…
Adiabatic Deceleration of Solar Energetic Particles as Deduced from Monte Carlo Simulations of Interplanetary Transport
Vainio, R.; Torsti, J.; Kocharov, L. +1 more
Monte Carlo simulations of interplanetary transport are employed to study adiabatic energy losses of solar protons during propagation in the interplanetary medium. We consider four models. The first model is based on the diffusion-convection equation. Three other models employ the focused transport approach. In the focused transport models, we sim…
Neutral Hydrogen Column Depths in Prominences Using EUV Absorption Features
Andretta, V.; Kucera, T. A.; Poland, A. I.
Observations of prominence regions in hot coronal lines (≳106 K) at wavelengths below the hydrogen Lyman absorption limit show what appear to be absorption features. Other authors have suggested that these observed features may be due to H and He continuum absorption. But there has, as yet, been no conclusive evidence that this is indeed the case.…
Coronal line-width variations
Doyle, J. G.; Banerjee, D.; Perez, M. E.
Line-width measurements of the coronal ion Siviii confirm earlier observations which show an increase in the non-thermal velocity above the solar limb. The present data, taken at the equatorial limb, show an increase from 24 km s-1 at the limb to 28 km s-1 some 25000 km above the limb. The electron density as measured from th…
Solar Wind Velocity and Anisotropic Coronal Kinetic Temperature Measured with the O VI Doublet Ratio
Giordano, S.; Antonucci, E.; Martin, R. +1 more
Doppler dimming of the O vi resonance lines (λ1032 Å, λ1037 Å) in an expanding corona is calculated including the pumping effect on the O vi λ1037.61 Å of both C ii lines at λ1036.34 Å and λ1037.02 Å, and the effect of the width of the absorption profiles of the coronal oxygen ions along the incident radiation. The pumping effect of the C ii line …
Observations of Coronal Structures Above an Active Region by EIT and Implications for Coronal Energy Deposition
Michels, D. J.; Thompson, B. J.; Gurman, J. B. +19 more
Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the temperature range of 1.0-2.0 MK. Such observations permit estimates of longitudinal temperature gradients (if present) in the corona and, conseque…
Heating Events in the Quiet Solar Corona
Krucker, Säm; Benz, Arnold O.
Sensitive observations of the quiet Sun observed by EIT on the SOHO satellite in high-temperature iron-line emission originating in the corona are presented. The thermal radiation of the quiet corona is found to fluctutate significantly, even on the shortest time scale of 2 min and in the faintest pixels. The power spectrum of the emission measure…