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A Direct Comparison Between EUV Coronal Flux and Helium Resonance Line Photon Flux from SOHO/CDS DataIn the wealth of EUV spectroscopic and imaging data gathered by the SOHO and TRACE missions, a prominent role is played by the helium resonance emission. For example, He I lines are among the most intense features in CDS/NIS spectra, while the EIT 304 waveband (dominated by He II emission) is routinely employed to map the structure of the solar chromosphere and transition region. However, no 'standard' model has emerged so far that is able to interpret observed He spectra/images to a satisfactory degree of self-consistency. Recent research on the problem of the formation of the solar helium spectrum tends to rule out a dominant role of coronal radiation in exciting He resonance lines. However, while evidence for this result is strong, it is based on indirect tests. Here we present a preliminary assessment of this issue based on a more direct approach, which involves a measure with CDS/GIS of the photoionizing EUV radiation. This measure can be directly compared with the observed flux in the main He I and He II resonance lines observed with CDS/NIS2.
Document ID
19990109152
Acquisition Source
Goddard Space Flight Center
Document Type
Other
Authors
Andretta, V.
(Osservatorio Astronomico, Capodimonte Naples, Italy)
Landi, Enrico
(Florence Univ. Italy)
DelZanna, Giulio
(University of Central Lancashire, Preston Lancashire, United Kingdom)
Jordan, Stuart D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1999
Subject Category
Solar Physics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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