The magnetic field of Sigma Orionis E

Abstract

A magnetic field has been detected in the peculiar variable helium-rich B2 star Sigma Ori E. The field varies between minus 2300 and plus 3100 gauss with the 1.19-day period of the spectroscopic and light variations of the star. It is suggested that the detection of this field allows all the variable phenomena of Sigma Ori E to be understood in terms of an oblique-rotator model in which hot gas is trapped in a magnetosphere above the magnetic equator and atmospheric helium enhancement has accurred preferentially in a magnetosphere above the magnetic equator and atmospheric helium enhancement has occurred preferentially in a zone around the magnetic equator.