SIMBAD references

New electron density diagnostic line ratios are presented for the Oiv 2s ² 2p ² P-2s2p ²⁴ P and Siv 3s ² 3p ² P-3s3p ²⁴ P intercombination lines around 1400Å. A comparison of these with observational data for the symbiotic star RR Telescopii (RR Tel), obtained with the Space Telescope Imaging Spectrograph (STIS), reveals generally very good agreement between theory and observation. However the Siv² P_3/2- ⁴ P_1/2transition at 1423.824Å is found to be blended with an unknown feature at 1423.774Å. The linewidth for the latter indicates that the feature arises from a species with a large ionization potential. In addition, the Siv² P_1/2- ⁴ P_3/2 transition at 1398.044Å is identified for the first time (to our knowledge) in an astrophysical source other than the Sun, and an improved wavelength of 1397.166 Å is measured for the Oiv² P_1/2- ⁴ P_3/2line. The Oiv and Siv line ratios in a sunspot plume spectrum, obtained with the Solar Ultraviolet Measurements of the Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory, are found to be consistent, and remove discrepancies noted in previous comparisons of these two ions.