X-ray aurora of the early magnetic B-type star HR 7355

As a decisive experiment to establish whether particle acceleration operates inmagnetic hot stars, we propose a joint XMM and NuSTAR observation of the B2Vstar HR7355. Nonthermal radio emissions have already been detected from HR7355.Our advanced 3D models predict rotationally modulated nonthermal Xrayemission from polar aurorae. XMM and NuSTAR observations are requested tovalidate this prediction. Detecting Xray aurorae will overturn the hithertoaccepted theory of Xray production in earlytype magnetic stars. The new datawill also provide important insights into the auroral mechanism operating inastronomical objects, from planets to massive stars. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]