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Modeling the magnetosphere of the B2Vp star σ Ori E

Published online by Cambridge University Press:  12 July 2011

Mary E. Oksala ,
Gregg A. Wade ,
Rich H. D. Townsend ,
Oleg Kochukhov  and
Stan P. Owocki
Mary E. Oksala
Affiliation:
Department of Physics and Astronomy, University of Delaware, Newark, DE, USA Department of Physics, Royal Military College of Canada, Kingston, Ontario, Canada
Gregg A. Wade
Affiliation:
Department of Physics, Royal Military College of Canada, Kingston, Ontario, Canada
Rich H. D. Townsend
Affiliation:
Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA
Oleg Kochukhov
Affiliation:
Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
Stan P. Owocki
Affiliation:
Bartol Research Institute, University of Delaware, Newark, DE, USA
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Abstract

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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. σ 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, Hα 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.

Keywords

stars: magnetic fieldsstars: rotationstars: early-typestars: circumstellar matterstars: individual (HD 37479)techniques: polarimetric
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S272: Active OB stars: structure, evolution, mass loss, and critical limits , July 2010 , pp. 124 - 129
Copyright
Copyright © International Astronomical Union 2011

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