Abstract
The anomalously strong OVI and NV lines in O stars and the CIV and Si IV lines in B supergiants may be due to Auger ionization by x-rays from a thin coronal zone at the base of their cool stellar winds. This paper summarizes the results of several studies to determine constraints on the size and temperature of coronal zones from calculations of the effects of coronae on continuum and line spectra. The model that has resulted can be tested by observations from HEAO-B of the predicted 2 kev emergent fluxes. The model explains very well the persistence of the OVI and NV in the ultraviolet spectra of supergiants to class B0.5 and B2 respectively, and it predicts that CIV should be observable in the ultraviolet spectra at and beyond B5I.
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