Relative emission line strengths for the sodium-like ions AL III and SI IV in the sun
Abstract
Recent R-matrix calculations of electron excitation rates for the Na-sequence ions Al III and Si IV are used to determine theoretical emission line ratios applicable to the solar transition region. A comparison of the Al III results with high resolution (≅0.06 Å) solar data obtained with the NRL S082-B spectrograph on board Skylab shows reasonable agreement between theory and observations. However a similar analysis for Si IV using low resolution (≅2 Å) EUV satellite spectra for the quiet sun and an active region reveals that the calculations and observational data are incompatible. It is shown that this is probably due to the Si IV 3d2D3/2 - 3p2P1/2 and 3d2D3/2,5/2 - 3p2P3/2 transitions at 1122.5 Å and 1128.3 Å respectively being blended with lines arising from ions with relatively low ionization potentials.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1986
- Bibcode:
- 1986A&A...169..319K
- Keywords:
-
- Emission Spectra;
- Ion Temperature;
- Sodium;
- Solar Electrons;
- Solar Spectra;
- Aluminum;
- Silicon;
- Spectral Energy Distribution;
- Solar Physics