Acceleration of mass flow in the chromosphere of α Orionis

The spectrum of α Orionis is composite and consists of four components arising from 1) the photosphere, 2) two distant shells expanding at constant velocities differing by 6-7 km/s and 3) a warm chromosphere in which the mass flow is being accelerated, perhaps to its terminal value in the inner shell. Calculations are presented on the feasibility of direct observational determinations of the heights and thicknesses of the chromospheric regions in bright giants and supergiants, using the technique of speckle interferometry and lunar occulations. (Auth.)