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Published online by Cambridge University Press: 23 September 2016
Fell lines are frequently observed in the optical spectra of early type emission line stars. Space observations of their ultraviolet spectra led to the discovery of a considerable line absorption due to ionized metal lines formed in the stellar envelopes. We describe some examples and show that spectral synthesis is required especially for the analysis of the low resolution spectra, and may provide information about the structure of the envelopes and the mass loss rates. We also discuss the Felll lines in the UV spectra of a Herbig Be star and of β Lyrae.