Resonances in Collision Strengths for Excitation of [O II] and [O III]

Abstract

The collision strength for the transition $$O^{+} 2s^{2}2p^{3} \,^{2}D_{3/2}-^{2}D_{5/2}$$ has a complicated resonance structure at energies below the threshold for excitation of $$O^{+} 2s^{2}2p^{3} \,^{2}P.$$ The collision strengths for the transitions $$O^{2+} 2s^{2}2p^{2} \,^{3}P^{-1}D, \,^{3}P^{-1}S \,\text{and} ^1{D}^{-1} S$$ contain near-threshold resonances due to collisional coupling between the configurations $$2s^{2}2p^{2} \,\text{and} \,2s2p^{3}.$$ The results obtained in recent calculations are presented in a form convenient for astrophysical applications. The resonances do not produce any large changes in the intensity ratios, [O II ] (λ 3729)/(λ 3726) and [O III ] (λ 4959 + λ 5007)/(λ 4363), as functions of electron temperature and electron density.