Line-driven ablation of circumstellar discs: II. Analyzing the role of multiple resonances

Abstract

We extend our previous study of radiative ablation of circumstellar disks by line-scattering of the star's radiation, accounting now for the effect of multiple line resonances off the stellar limb. For an analytic, three-dimensional model of the velocity structure of an equatorial Keplerian disk bounded at higher latitudes by a radially accelerating stellar wind outflow, we use root-finding methods to identify multiple resonances from a near-disk circumstellar location along starward rays both on and off the stellar core. Compared to our previous study that accounted only for the effect of on-core resonances in reducing the radiative driving through the scattering of radiation away from a near-disk circumstellar location, including off-limb resonances leads to additional radiative driving from scattering toward this location. Instead of the up-to-50% reduction in line-acceleration previously inferred from multiple resonance effects, we now find a more modest 15-20% net reduction.