Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

Elemental abundances in the solar corona are known to be different from those observed in the solar photosphere. The ratio of coronal to photospheric abundance shows a dependence on the first ionization potential (FIP) of the element. We estimate FIP bias from direct measurements of elemental abunda...

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Bibliographic Details
Published in:Solar physics 2020-12, Vol.295 (12), Article 175
Main Authors: Narendranath, Shyama, Sreekumar, P., Pillai, Netra S., Panini, Singam, Sankarasubramanian, K, Huovelin, Juhani
Format: Article
Language:English
Subjects:
Abundance
Astrophysics and Astroparticles
Atmospheric Sciences
Bias
Chromosphere
Corona
First ionization potential
Fractionation
Ionization
Photosphere
Physics
Physics and Astronomy
Soft x rays
Solar activity
Solar corona
Solar physics
Space Exploration and Astronautics
Space missions
Space Sciences (including Extraterrestrial Physics
Spectroscopy
Spectrum analysis
Wave propagation
X ray spectra
X-ray spectroscopy
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Summary:Elemental abundances in the solar corona are known to be different from those observed in the solar photosphere. The ratio of coronal to photospheric abundance shows a dependence on the first ionization potential (FIP) of the element. We estimate FIP bias from direct measurements of elemental abundances from soft X-ray spectra using data from multiple space missions covering a range of solar activity levels. This comprehensive analysis shows clear evidence for a decrease in FIP bias around the maximum intensity of the X-ray flare with coronal abundances briefly tending to photospheric values and a slow recovery as the flare decays. The departure from coronal abundances are larger for the low FIP elements Ca, Fe and Si than for S which have a mid FIP value. These changes in the degree of fractionation might provide inputs to model wave propagation through the chromosphere during flares.
ISSN:0038-0938
1573-093X
DOI:10.1007/s11207-020-01738-5