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   PR # 41017
   The X-ray emission mechanism of early type star is still unresolved
   problem. ROSAT observed an flare-up of zeta Ori, and they concluded
   that the X-rays are emitted by an expanding hot wind heated by a
   ploughing wind shock, from observed light curve. This conclusion
   might have some room for doubt. We propose to observe a time
   variation of zeta Ori and to study the temporal evolution of the
   plasma temperature and ionization parameters. This observation will
   provide rigid conclusion of the X-ray emission mechanism of early
   type stars.
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