Variability of EUV-spectra from the quiet upper solar atmosphere: Intensity and Doppler shift
Abstract
We have studied SUMER and CDS time series of spectra and images of quiet-Sun regions at the solar disc centre. The data contain ultraviolet emission lines sampling temperatures of the chromosphere, transition region and corona. We find a high correlation between average net Doppler shifts and relative brightness variabilities of the studied lines (correlation coefficient of 0.92), suggesting a connection between the two quantities. The anti-correlation between differential emission measures and relative brightness variabilities is weaker (correlation coefficient of -0.78). We discuss the observed relationships on the basis of differential emission measures and linear wave calculations.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 2003
- DOI:
- 10.1051/0004-6361:20030400
- Bibcode:
- 2003A&A...403..725B
- Keywords:
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- Sun: chromosphere;
- Sun: corona;
- Sun: transition region;
- Sun: UV radiation