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Observation and Modeling of the Solar Transition RegionWe report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.
Document ID
20000068433
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Oluseyi, Hakeem M.
(Stanford Univ. Stanford, CA United States)
Walker, A. B. C., II
(Stanford Univ. Stanford, CA United States)
Porter, Jason
(NASA Marshall Space Flight Center Huntsville, AL United States)
Hoover, Richard B.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Barbee, Troy W., Jr.
(Lawrence Livermore National Lab. Livermore, CA United States)
Date Acquired
August 19, 2013
Publication Date
October 20, 1999
Publication Information
Publication: Astrophysical Journal
Publisher: American Astronomical Society
Volume: 524
Subject Category
Solar Physics
Funding Number(s)
CONTRACT_GRANT: W-7405-eng-48
CONTRACT_GRANT: NsG-5131
Distribution Limits
Public
Copyright
Other

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