Search Publications
Ly-α Observation of a Coronal Streamer with UVCS/SOHO
Romoli, M.; Modigliani, A.; Fineschi, S. +3 more
In this paper we discuss some characteristics of an equatorial streamer observed by UVCS in July 1997. We determine the height distribution of the Ly-α total intensity and of its width. We focus our attention, in particular, on the time variability of these parameters.
Signatures of Coronal Hole Spectra Between 660 Å and 1460 Å Measured with SUMER on SOHO
Solanki, S. K.; Wilhelm, K.; Curdt, W. +2 more
Spectra of the northern polar coronal hole measured with the SUMER spectrometer on SOHO on 25 October 1996 are analyzed. We present spectra taken at locations on the solar disk where part of the spectrometer slit intersects a polar coronal hole region and an area of brighter emission from outside of the coronal hole area. By comparing the line int…
On the Electron Temperature and Coronal Heating in the Fast Solar Wind Constrained by in-situ Observations
Ko, Y. -K.; Groth, C. P. T.
The electron temperature profile in the polar coronal hole inferred by the ionic charge state data of the fast wind exhibits a local maximum of ∼ 1.5 × 106 K. This indicates the existence of electron heating in the source region of the fast solar wind. In this paper, a two-fluid solar wind model, which incorporates additional 'mechanica…
Review, based on particles and fields observations made aboard the Giotto spacecraft, concerning the nature of the solar wind interaction with comets P/Halley and P/Grigg Skjellerup
McKenna-Lawlor, Susan M. P.
A key driver underlying the decision to command the Giotto spacecraft on to an encounter with comet P/Grigg-Skjellerup following its highly successful encounter with P/Halley, was the unique scientific opportunity this provided to compare measurements made using the same suite of plasma and fields instruments at (a) very active and 'fresh' comet P…
Large-scale Coronal Heating, Clustering of Coronal Bright Points, and Concentration of Magnetic Flux
Falconer, D. A.; Moore, R. L.; Porter, J. G. +1 more
By combining quiet-region Fe XII coronal images from SOHO/EIT with magnetograms from NSO/Kitt Peak and from SOHO/MDI, we show that the population of network coronal bright points and the magnetic flux content of the network are both markedly greater under the bright half of the large-scale quiet corona than under the dim half. These results (1) su…
UVCS Observations and Modeling of Streamers
Raymond, J. C.; van Ballegooijen, A. A.; Vásquez, A. M.
We present results derived from the analysis of an equatorial streamer structure as observed by the UVCS instrument aboard SOHO. From observations of the H I Lyα and Lyβ lines we infer the density and temperature of the plasma. We develop a preliminary axisymmetric, magnetostatic model of the corona which includes the effects of gas pressure gradi…
Loop Models from SOHO Observations
Landini, M.; Solanki, S.; Landi, E. +2 more
The Coronal Diagnostic Spectrometer (CDS) on SOHO is a grazing/normal incidence spectrograph, aimed to produce stigmatic spectra of selected regions of the solar surface in six spectral windows of the extreme ultraviolet from 150 Å to 785 Å (Harrison et al. 1995). In the present work, CDS, EIT, MDI and Yohkoh observations of active region lops hav…
Ulysses-UVCS Coordinated Observations
Romoli, M.; Poletto, G.; Kohl, J. +5 more
We present results from SOHO/UVCS measurements of the density and flow speed of plasma at the Sun and again of the same plasma by Ulysses/SWOOPS in the solar wind. UVCS made measurements at 3.5 and 4.5 solar radii and Ulysses was at 5.1 AU. Data were taken for nearly 2 weeks in May June 1997 at 9 10 degrees north of the equator in the streamer bel…
The Highest Solar Wind Velocity in a Polar Region Estimated from IPS Tomography Analysis
Tokumaru, M.; Kojima, M.; Fujiki, K. +3 more
EUV and Radio Observations of an Equatorial Coronal Hole
Kerdraon, A.; Fludra, A.; Landi, E. +1 more
An equatorial coronal hole has been observed on 18 and 19 October 1996 with SOHO-CDS and with the Nancąy Radioheliograph (RH). The CDS EUV line intensities are used to determine the coronal hole Differential Emission Measure (DEM); in turn this is used to compute the radio brightness temperature Tb at the observed frequencies, leaving t…