We have used UV spectra from solar flares observed with SOHO/SUMER and Skylab to identify all of the all remaining unidentified forbidden lines arising from transitions within levels of the Fe XX ground configuration. We have also obtained more accurate wavelengths for previously observed lines. Forbidden lines resulting from transitions within levels of the ground configuration of highly ionized elements generally have longer wavelengths than resonance lines emitted by the same ions. Many of these forbidden lines are fairly prominent in low-density plasmas, and have traditionally been used in determining properties of high temperature astrophysical plasmas. The identified Fe XX forbidden lines span the 300-2665 Angstroms wavelength range. Since spontaneous decay rates of forbidden transitions arising from the same upper level are known quite accurately, these lines can be used for calibrating spectrometers over wide wavelength ranges.
AAS/Solar Physics Division Meeting #31
- Pub Date:
- May 2000