Emission-line ratios for O III in gaseous nebulae and a comparison between theory and observation

Recent R-matrix calculations of electron excitation rates in O III are used to derive electron temperature and density-sensitive emission-line ratios R1 = I(2322 A)/I(1661 A + 1667 A), R2 = I(1661 A + 1667 A)/I(4960 A + 5009 A), and R3 = I(4363 A)/I(4960 A + 5009 A) for a range of Te (7500-40,000 K) and Ne 10 to the 2nd to 10 to the 7th/cu cm applicable to gaseous nebulae. Electron temperatures and densities deduced from these and observed values of R1, R2, and R3 for several planetary nebulae and a Seyfert galaxy in general show good internal agreement and also compare favorably with results deduced from the line ratios of other species, thereby providing support for the atomic data adopted in the calculations. 29 references