Shell and photosphere of OMI ORI E : new observations and improved model.

Abstract

Phase-dependent IR fluxes in the J, H, K, L, and M bands, together with visual spectrograms and IUE spectra, are used to study the helium-rich star Sigma Ori E. An effective temperature of about 22,500 K is derived, along with an angular diameter of 0.079 milliarcsec, a surface gravity of log g equals 3.85, and a mass of approximately 3 solar masses. It is shown that the star probably has not completed its pre-main-sequence contraction and is an oblique rotator with a large helium cap and two corotating clouds located almost oppositely near the intersections of the magnetic and rotational equators at a distance of 2 stellar radii.