The chromosphere above sunspot umbrae. III - Spatial and temporal variations of chromospheric lines
Abstract
The lines Ca II H, K, 8542 A, Na I D(1) and D(2), Ni I 5893 A, and H-alpha, were analyzed in photographic spectrograms obtained from a sunspot. The following results are found for the umbra: (1) the H and K lines are highly correlated, with an emission cores maximum-intensities ratio of 1.2; (2) the K intensities are poorly correlated with those of 8542, D(2), and H-alpha; this behavior is attributed to atmospheric structure horizontal fluctuations having little correlations between those in high and low layers, (3) the periodic temporal fluctuations of the K emission core with umbral flashes are identified, and found to occur throughout the umbral area covered by the spectrograph slit; and (4) fluctuations in the photospheric Ni I 5893 A line cannot be matched to the chromospheric fluctuations, in accord with Giovanelli (1978).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1981
- Bibcode:
- 1981A&A...102..147K
- Keywords:
-
- Chromosphere;
- Solar Spectra;
- Spatial Distribution;
- Spectral Line Width;
- Sunspots;
- Temporal Distribution;
- Astronomical Photography;
- Calcium;
- H Lines;
- K Lines;
- Solar Atmosphere;
- Spectral Energy Distribution;
- Umbras;
- Solar Physics