Discrete Absorption Components from 3-D spot models of hot star winds

TL;DR

This paper uses 3-D radiation-hydrodynamic models to simulate how magnetic spots on hot stars can produce spiral wind structures that lead to observable discrete absorption components in UV spectra.

Contribution

It introduces novel 3-D models linking stellar surface spots to wind structures and spectral features, advancing understanding of wind variability in hot stars.

Findings

Spiral structures form due to magnetic spots.

Synthetic spectra show DAC signatures.

Models explain observed wind variability.

Abstract

The winds of hot, massive stars are variable from processes happening on both large and small spatial scales. A particular case of such wind variability is 'discrete-absorption components' (DACs) that manifest themselves as outward moving density features in UV resonance line spectra. Such DACs are believed to be caused by large-scale spiral-shaped density structures in the stellar wind. We consider novel 3-D radiation-hydrodynamic models of rotating hot star winds and study the emergence of co-rotating spiral structures due to a local (pseudo-)magnetic spot on the stellar surface. Subsequently, the hydrodynamic models are used to retrieve DAC spectral signatures in synthetic UV spectra created from a 3-D short characteristics radiative transfer code.