Coronal abundances in solar active regions measured by the Solar Maximum Mission flat crystal spectrometerHigh resolution soft X-ray spectra acquired by the Flat Crystal Spectrometer (FCS) on solar Maximum Mission provide an excellent data base to study the relative abundances of O, Ne, Mg, and Fe in solar active regions. The FCS data show significant variability for all combinations of these elements. The largest variation occurs for Fe:Ne, which shows region to region changes of up to a factor of 7, and frequent factor of 2 variations in day to day samples of a given region. The atomic data and the ionization balance calculations used to interpret the line ratios affect the actual abundance values obtained, but have little effect on the magnitude of the total range of variation inferred. Resonance scattering of Fe XVII could cause a systematic offset in the abundances determined, but cannot be responsbile for the bulk of the observed variability. While abundance variability complicates the derivation of plasma parameters from spectroscopic measurements, it should offer exciting new clues to the processes which form and heat the corona.
Document ID
19930022227
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Saba, Julia L. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Strong, Keith T. (Lockheed Aircraft Corp. Palo Alto, CA., United States)
Date Acquired
September 6, 2013
Publication Date
November 1, 1992
Publication Information
Publication: ESA, Proceedings of the First SOHO Workshop: Coronal Streamers, Coronal Loops, and Coronal and Solar Wind Composition