Abstract
Results are presented of a first session of a program run at the Catania Astrophysical Observatory to study and monitor the H-alpha emission from early-type stars, and the properties of their mass loss are determined. Twelve early-type supergiants in the Cygnus region were observed repeatedly in 1988 July. From these observations, evidence is found for short-term variability of the mass-loss rate. Also, a comparison with literature data reveals strong long-term variations for some of the stars. In addition, simplified models were developed to describe the H-alpha profile resulting from the combination of photospheric absorption with emission and scattering in the wind. By fitting the observed profiles with the models, the mass-loss rates and the velocity fields are determined for all stars with accuracies generally better than 25 percent.
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