Detecting the Zeeman effect in Massive Star Magnetospheres in the UV

TL;DR

This paper explores the potential of using UV spectropolarimetry to detect Zeeman effect signatures in massive star winds, offering a new method to study magnetic fields influencing stellar evolution.

Contribution

It introduces the possibility of detecting Zeeman signatures in UV resonance lines, expanding magnetic field diagnostics beyond optical lines for massive stars.

Findings

UV spectropolarimetry can reveal magnetic fields in stellar winds

Potential for high-sensitivity spaceborne UV instruments like POLSTAR

New diagnostic method for massive star magnetospheres

Abstract

Approximately 7% of massive stars host stable surface magnetic fields that are strong enough to alter stellar evolution through their effect on the stellar wind. It is therefore crucial to characterize the strength and structure of these large-scale fields in order to quantify their influence on massive star evolution. This is traditionally done by measuring the circular polarization caused by Zeeman splitting in optical photospheric lines, but we investigate here the possibility of detecting Stokes $V$ signatures in the wind-sensitive resonance lines formed in magnetically confined winds in the high opacity ultraviolet (UV) domain. This unique diagnostic would be accessible to high-sensitivity spaceborne UV spectropolarimeters such as POLSTAR.