O I 8446 A emission in Seyfert 1 galaxies

Broad O I 8446 A emission is seen in 13 of 16 observed Seyfert 1 galaxies with strengths compared to H alpha ranging from 0.01 to 0.07. It is found that the excitation mechanism of O I 8446 A in Seyfert galaxies must be L beta pumping in a Bowen fluorescence process. Recent calculations (Ferland and Netzer, 1979; Kwan and Krolik, 1979) regarding radiative transfer show that deep within the cloud, where H and O are largely neutral, trapped L alpha photons will populate the n = 2 levels of H, and Balmer continuum ionization and collisional excitation by electrons, a result of ionizations by diffuse He radiation, will produce L beta photons. Calculations indicate that observed values of the (8446 A)/(H alpha) ratio can be reproduced in this manner.