The Role of Far-ultraviolet Pumping in Exciting the [O i] Lines in Protostellar Disks and Winds

Abstract

We use Cloudy to re-examine excitation of [O i ] 6300 Å and [O i ] 5577 Å in the X-ray driven photoevaporative wind models of Owen and collaborators, and in more recent magnetothermal models by Wang et al. We find that, at the measured accretion luminosities, the far-ultraviolet (FUV) radiation would populate the upper levels of the oxygen, which would eventually contribute to the [O i ] lines. FUV pumping competes with collisions as an excitation mechanism of the [O i ] lines, and they each originate from a distinct region in the protostellar disk environment. Consequently, the line strengths and shapes of [O i ] 6300 Å and [O i ] 5577 Å would be affected by the inclusion of FUV pumping in the radiation transport simulations.