What Determines Active Region Coronal Plasma Composition?

The chemical composition of the solar corona is different from that of the solar photosphere, with the strongest variation being observed in active regions (ARs). Using data from the Extreme Ultraviolet (EUV) Imaging Spectrometer (EIS) on Hinode, we present a survey of coronal elemental composition...

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Bibliographic Details
Published in:The Astrophysical journal 2022-07, Vol.933 (2), p.245
Main Authors: Mihailescu, Teodora, Baker, Deborah, Green, Lucie M., van Driel-Gesztelyi, Lidia, Long, David M., Brooks, David H., To, Andy S. H.
Format: Article
Language:English
Subjects:
Astrophysics
Bias
Chemical composition
Corona
Evolution
First ionization potential
Fluctuations
Flux density
Imaging spectrometers
Ionization
Magnetic flux
Photosphere
Plasma composition
Sciences of the Universe
Solar abundances
Solar active regions
Solar corona
Solar wind
Trends
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Summary:The chemical composition of the solar corona is different from that of the solar photosphere, with the strongest variation being observed in active regions (ARs). Using data from the Extreme Ultraviolet (EUV) Imaging Spectrometer (EIS) on Hinode, we present a survey of coronal elemental composition as expressed in the first ionization potential (FIP) bias in 28 ARs of different ages and magnetic flux content, which are at different stages in their evolution. We find no correlation between the FIP bias of an AR and its total unsigned magnetic flux or age. However, there is a weak dependence of FIP bias on the evolutionary stage, decreasing from 1.9 to 2.2 in ARs with spots to 1.5–1.6 in ARs that are at more advanced stages of the decay phase. FIP bias shows an increasing trend with average magnetic flux density up to 200 G, but this trend does not continue at higher values. The FIP bias distribution within ARs has a spread between 0.4 and 1. The largest spread is observed in very dispersed ARs. We attribute this to a range of physical processes taking place in these ARs, including processes associated with filament channel formation. These findings indicate that, while some general trends can be observed, the processes influencing the composition of an AR are complex and specific to its evolution, magnetic configuration, or environment. The spread of FIP bias values in ARs shows a broad match with that previously observed in situ in the slow solar wind.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac6e40