Discovery of X-ray flaring on the magnetic Bp-star $\mathsf{\sigma}$ Ori E

Abstract

We report the detection of an X-ray flare on the Bp star σ Ori E with the ROSAT high resolution imager (HRI). The flare is shown to have likely occurred on the early-type star, rather than on an hypothesized late-type companion. We derive flare parameters such as total energy release, coarse estimates of size and density, and also present arguments for a magnetic origin of the flare. We place our observations in the context of a magnetic character of Bp-type stars and speculate on a common physical basis and connection between Bp and Be stars.