Ultraviolet spectroscopy of F and G supergiants with IUE. I - First results of Cepheid variables

The analysis deals with the bright Cepheids observed from the IUE satellite, over several days, at a speed and spectral resolution suitable to study both the cores of Mg II at 2796 and 2803 A and the presence and strength of the more prominent emission lines in the far ultraviolet. The observations are discussed in some detail. Some qualitative results are examined.