Modeling the Magnetosphere of the B2Vp star sigma Ori E

TL;DR

This study models the magnetic field and magnetosphere of sigma Ori E using spectropolarimetric data, applying the RRM model and Magnetic Doppler Imaging to understand its magnetic and plasma environment.

Contribution

It applies the RRM model to sigma Ori E's observed data and discusses the potential of Magnetic Doppler Imaging for future surface abundance mapping.

Findings

The RRM model approximately reproduces observed magnetic and photometric variations.

Small discrepancies in the light curve suggest inhomogeneous surface abundances.

Future work will use Magnetic Doppler Imaging to distinguish abundance spots from circumstellar effects.

Abstract

This paper presents results obtained from Stokes I and V spectra of the B2Vp star sigma Ori E, observed by both the Narval and ESPaDOnS spectropolarimeters. Using Least- Squares Deconvolution, we investigate the longitudinal magnetic field at the current epoch, including period analysis exploiting current and historical data. sigma Ori E is the prototypical helium-strong star that has been shown to harbor a strong magnetic field, as well as a magnetosphere, consisting of two clouds of plasma forced by magnetic and centrifugal forces to co-rotate with the star on its 1.19 day period. The Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005) approximately reproduces the observed variations in longitudinal field strength, photometric brightness, Halpha emission, and various other observables. There are, however, small discrepancies between the observations and model in the photometric light curve, which we propose arise from inhomogeneous chemical abundances on the star's surface. Using Magnetic Doppler Imaging (MDI), future work will attempt to identify the contributions to the photometric variation due to abundance spots and due to circumstellar material.