The O IV infrared and ultraviolet flux ratios as temperature and density diagnostics.

Abstract

New fine-structure collision strengths for transitions among the levels of the first two terms of O⁺³ are presented. The density sensitivity of the intensity ratios of the components of the intercombination multiplet at 1401 Å is re-evaluated for densities and temperatures applicable to planetary nebulae. The authors also show that the intensity ratio of the fine-structure line at 25.9 μm to the 1401 Å multiplet provides a diagnostic for electron temperature. The effect of radiation fields on the intensity ratios is investigated.