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Inferring the Coronal Density Irregularity from EUV Spectra

Hahn, Michael; Savin, Daniel Wolf

Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present a new method for quantifying such structures using density-sensitive extreme ultraviolet line intensities to derive a density irregularity parameter, a relative measure of the amount of structure along the line of sight. We also present a simple model to relate the inferred irregularities to physical quantities, such as the filling factor and density contrast. For quiet-Sun regions and interplume regions of coronal holes, we find a density contrast of at least a factor of 3–10 and corresponding filling factors of about 10%–20%. Our results are in rough agreement with other estimates of the density structures in these regions. The irregularity diagnostic provides a useful relative measure of unresolved structure in various regions of the corona.

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Published In
The Astrophysical Journal
Publisher DOI
https://doi.org/10.3847/0004-637X/829/1/42
Volume
829
Pages
1 - 12
Academic Units
Astrophysics Laboratory
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