Physical Sciences and Mathematics Commons^™

Pumping Up The [N I] Nebular Lines, Gary J. Ferland, W. J. Henney, C. R. O'Dell, R. L. Porter, P. A. M. Vanhoof, R. J. R. Williams

Physics and Astronomy Faculty Publications

The optical [N I] doublet near 5200 Å is anomalously strong in a variety of emission-line objects. We compute a detailed photoionization model and use it to show that pumping by far-ultraviolet (FUV) stellar radiation previously posited as a general explanation applies to the Orion Nebula (M42) and its companion M43; but, it is unlikely to explain planetary nebulae and supernova remnants. Our models establish that the observed nearly constant equivalent width of [N I] with respect to the dust-scattered stellar continuum depends primarily on three factors: the FUV to visual-band flux ratio of the stellar population, the optical properties …