******************************************************
   PR # 22022
    We wish to continue our program to understand the X-ray spectrum from
    O stars by observing Zeta Ori (O9.5Ib)w/ ASCA. Zeta Ori shows a rich 
    thermal spectrum with at least 2 temperatures.  Recent PSPC observ.  
    by Berghofer and Schmitt (1994) have discovered that the X-ray       
    emission is variable on a timescale of days in flux level & hardness.
    ASCA spectra will address the following questions: 1) What is the tem
    perature distribution of the emission? 2) Can we confirm the presence
    of a  hard, non-thermal X-ray tails suggested by the SSS data? 3)Does
    the observed line emission indicate any evidence of mixing in the    
    outer atmosphere? and 4)What is the level of variability of the X-ray
    emission in the long ASCA pointing, and how does this compare w/ the 
   variability seen by the PSPC? 
 ******************************************************