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Comparison of Polar and Equatorial Coronal Holes Observed by UVCS/SOHO: Geometry and Physical Properties
Dobrzycka, D.; Kohl, J.; Strachan, L. +1 more
We analyzed UVCS/SOHO data and compared the H I Lyα (121.6 nm) and O VI (103.2 nm, 103.7 nm) emission in the polar and equatorial coronal holes. We found that the emission lines have similar characteristics in these two types of coronal holes. Both types show evidence for superradially diverging boundaries. The latitudinal distribution of the O VI…
Working Group 3 Report: Coronal Hole Boundaries and Interactions with Adjacent Regions
Esser, R.
Summarized below are the discussions of working group 3 on "Coronal hole boundaries and interactions with adjacent regions" which took place at the 7th SOHO workshop in Northeast Harbor, Maine, USA, 28 September to 1 October 1998. A number of recent observational and theoretical results were presented during the discussions to shed light on differ…
Comparing Quiet Sun and Coronal Hole Regions with CDS/SOHO
Young, P. R.; Esser, R.
Spectra from the Coronal Diagnostic Spectrometer on board SOHO are used to compare density and temperature in coronal hole and quiet Sun regions.
Observation of Transition Region Fine Structures with Soho/Sumer
Mason, H. E.; Landini, M.; Landi, E.
We present a preliminary analysis of two quiet Sun transition region areas observed with the SOHO/SUMER spectrometer, using lines from oxygen, nitrogen and silicon. The average quiet Sun physical parameters are studied as a function of line intensity. Systematic variations of line position and width with increasing intensity are found. A large num…
Working Group 2 Report: Energy Input, Heating, and Solar Wind Acceleration in Coronal Holes
Hood, A. W.
Theories and observations of energy input, heating and acceleration mechanisms in the low corona were presented and discussed. The main topics of discussion were large-scale solar wind simulations, theoretical heating mechanisms, observational constraints, confronting theory with observations and observational issues.
Outflow Velocities at the Base of a Polar Coronal Hole During the 1998 Total Eclipse
Vial, J. -C.; Koutchmy, S.; Patsourakos, S. +2 more
Polar coronal holes represent the most convincing site from which the high-speed solar wind originates. Here we report high-accuracy Doppler shifts measured in the O VI (1037.6 Å) line obtained by SUMER on SOHO inside an interplume region within the south polar coronal hole. We infer limits on the outflow velocity and draw hints about the flow geo…
On the Lyman α and O VI Line Profiles in Streamers and Coronal Holes
Poletto, G.; Noci, G.; Nicolosi, P. +1 more
The profiles of the Lyα line at 1215.6 Å and of the O VI doublet at 1031.9 Å and 1037.6 Å in the extended solar corona have been analyzed vs. latitude and radial direction, performing observations with the Ultraviolet Coronagraph Spectrometer (UVCS) on board the ESA-NASA solar satellite SOHO (Solar and Heliospheric Observatory). The results show t…
SOHO Observations of Density Fluctuations in Coronal Holes
Romoli, M.; Poletto, G.; Noci, G. +5 more
In recent UVCS/SOHO White Light Channel (WLC) observations we found quasi-periodic variations in the polarized brightness (pB) in the polar coronal holes at heliocentric distances of 1.9 to 2.45 solar radii. The motivation for the observation is the 2.5D MHD model of solar wind acceleration by nonlinear waves, that predicts compressive fluctuation…
SOHO After 30 Months: A Personal View
Gabriel, A. H.
Corotating Interaction Regions. Proceedings. ISSI Workshop, Bern (Switzerland), 6 - 13 Jun 1998.
Balogh, A.; Kunow, H.; Gosling, J. T. +2 more
The following topics were dealt with: solar wind corotating interaction regions, stream interfaces, satellite observations, turbulence, energetic particle transport, cosmic rays, CIR solar origin, high-latitude CIRs, outer heliosphere.