Unraveling the variability of sigma Ori E

TL;DR

This paper uses magnetic Doppler imaging and spectropolarimetric data to map the magnetic and elemental surface features of sigma Ori E, aiming to explain its optical variability beyond existing models.

Contribution

It provides detailed magnetic and abundance maps of sigma Ori E and analyzes their impact on brightness variability, addressing unexplained features in the star's light curve.

Findings

Magnetic field topology mapped via MDI.

Elemental abundance distributions identified.

Surface inhomogeneities linked to brightness variations.

Abstract

Sigma Ori E (HD 37479) is the prototypical helium-strong star shown to harbor a strong magnetic field, as well as a magnetosphere consisting of two clouds of plasma. The observed optical (ubvy) light curve of sigma Ori E is dominated by eclipse features due to circumstellar material, however, there remain additional features unexplained by the Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki. Using the technique of magnetic Doppler imaging (MDI), spectropolarimetric observations of sigma Ori E are used to produce maps of both the magnetic field topology and various elemental abundance distributions. We also present an analysis utilizing these computed MDI maps in conjunction with NLTE TLUSTY models to study the optical brightness variability of this star arising from surface inhomogeneities. It has been suggested that this physical phenomena may be responsible for the light curve inconsistencies between the model and observations.