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Line formation in the extended atmosphere of HD 50896 is studied using previously described modelling techniques. A model for the extended envelope of HD 50896 is presented which is shown to yield a continuous flux distribution, line strengths, and line profiles in good agreement with those observed. The model has a mass loss rate of 5 x 10 to the -5th solar mass/yr, core radius of 2.5 solar radii, luminosity of 50,000-100,000 solar, and stellar wind velocity of roughly 1600 km/s. Where in the extended envelope the emission lines are formed is investigated, and the effect of hydrogen on the He II line strengths is examined. The effect of mass loss rate, luminosity, core radius, and temperature distribution on the He II line profiles is examined, and discrepancies between theory and observation are discussed. Constraints on the extended envelope of HD 50896 are addressed, indicating how these might be improved by future modelling and observations.
D. J. Hillier (Wed,) studied this question.