Non-Axisymmetric Line Driven Disc Winds II - Full Velocity Gradient

TL;DR

This paper investigates 3D non-axisymmetric line-driven disc winds using the Sobolev approximation with full velocity gradients, revealing clump formation at the wind base and their potential observational signatures.

Contribution

It introduces a detailed analysis of non-axisymmetric features in line-driven winds considering the full velocity gradient, highlighting clump formation and their observational implications.

Findings

Clumps form mainly at the wind base on super-Sobolev scales.

Clump density varies by a factor of about 3 from azimuthal average.

Clumps cause approximately 20% variations in column density.

Abstract

We study non-axisymetric features of 3D line driven winds in the Sobolev approximation, where the optical depth is calculated using the full velocity gradient. We find that non-axisymmetric density features, so called clumps, form primarily at the base of the wind on super-Sobolev length scales. The density of clumps differs by a factor of $\sim 3$ from the azimuthal average, the magnitude of their velocity dispersion is comparable to the flow velocity and they produce $\sim 20\%$ variations in the column density. Clumps may be observable because differences in density produce enhancements in emission and absorption profiles or through their velocity dispersion which enhances line broadening.