Theoretical Line Profiles in the Ultraviolet Spectra of Early-Type Stars.

Tkeoretical ultraviolet spectra of two early B stars have been computed in detail from 911.6 to 3000 A, including all lines expected to be wider than about 2 A. The lines were assumed to be formed in pure absorption Perturbations of both ions and electrons were included in the broadening of the hydrogen lines, while a Doppler-damping profile with a damping constant ten times the classical value was used for all other elements. Most of the lines are found shortward of 1410 A where they have deep cores and many have extensive wings These overlapping lines cause significant blanketing, amounting to at least 31 per cent of the total flux at T = 25673 K and at least 20 per cent at T, = 31023 K. This effect must be included in the constant-flux criterion when computing the model atmospheres