Absolute ultraviolet spectrophotometry from the TD-1 satellite. VI. Statistical study of the 1930 Å Fe III absorption feature in early type stars.

Summary. The depth of the t930 A feature, attributed to Fe iii, has been measured in more than 300 early type star spectra obtained with the S2/68 U.V. sky survey telescope. The behaviour of this feature versus the visual index Q is correlated to the ionized equilibrium of Fe but it also shows an important luminosity effect. It increases from dwarfs to supergiants and is usually stronger in rapidly rotating Be stars and shell stars. Key words: early type stars, ultraviolet spectrophotometry, Fe iii absorption, Be stars, shell stars