HR: 0830h
AN: SP21B-08    [Abstracts]
TI: Properties of the Solar Corona Outside the West Solar Limb
AU: * Doschek, G A
EM: gdoschek@ssd5.nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Avenue, S.W., Washington, DC 20375-5320 United States
AU: Feldman, U
EM: ufeldman@ssd5.nrl.navy.mil
AF: Artep Inc., 2922 Excelsior Springs Court, Ellicott City, MD 21042 United States
AU: Landi, E
EM: landi@poppeo.nrl.navy.mil
AF: Artep Inc., 2922 Excelsior Springs Court, Ellicott City, MD 21042 United States
AB: We discuss the analysis of 36 spectral observations recorded by the SUMER spectrometer on SOHO on April 22-23, 1998, at the onset of the new solar cycle. The observations were made with the 4" x 300" slit, and are distributed over the west hemisphere between 1.02 and 1.5 solar radii along the equatorial direction and between -0.9 solar radii south of the equator and +0.9 solar radii north of it. At the far corners of the studied region the solar distance was 1.74 solar radii. We have found that the physical characteristics of the central part of the region are typical of quiet Sun coronal plasmas. The regions furthest from the equator resemble coronal hole plasmas and the intermediate regions are consistent with a transition between the two. We believe that this is the most comprehensive work of its kind undertaken thus far using UV spectral lines. We use the recorded line intensities and line shapes to describe, as a function of coronal position, electron temperatures, electron densities, elemental abundances, line-of-sight emission measures (EM), nonthermal mass motions, and mass dependent elemental settling. By using intensity ratios between the two component resonance lines of Li-like O VI, Ne VIII and Mg X, we determine the fractional excitation in the Li-like lines produced by electron collisions and the fractional excitation produced by photo-excitation of transition region radiation emitted just above the photosphere.
DE: 7509 Corona
DE: 7549 Ultraviolet emissions
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly