The Plasma Filling Factor of Coronal Bright Points
Abstract
Rastered spectra of regions of the quiet Sun were recorded by the Extreme ultraviolet Imaging Spectrometer (EIS) during operations with the Hinode satellite. Calibrated intensities of Fe XII lines were obtained and images of the quiet corona were constructed. From the imaged spectra, the emission measures and geometrical widths of coronal bright points were obtained. From density-sensitive line ratios, electron densities were determined. A comparison of the emission measure and bright point widths with the electron densities yielded the plasma-filling factor. The median electron density of coronal bright points is 2.5 × 109 cm-3 at a temperature of 1.4 × 106K. The volumetric plasma filling factor of coronal bright points was found to vary from 3 × 10-3 to unity with a median value of 0.02. The small filling factors lends support to theories, such as the nanoflare theory of Parker, that suggest coronal heating occurs on small spatial scales.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2008
- Bibcode:
- 2008AGUSMSP31D..04D
- Keywords:
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- 7509 Corona;
- 7549 Ultraviolet emissions