Spectrophotometric Investigations of Some o- and B-Type Stars Connected with the Orion Nebula

Photometric and spectrophotometric measures of a number of early-type stars con- nected with the Orion nebula are given for the wave-lengths between 4000 and 9000 A. The results show that most of the stars are affected by strong selective absorption which increases rapidly from 9000 to ôooo A to a nearly constant value for the shorter wave-lengths between 6ooo and 4QQOA. If we assume that the absorption is due to dust particles, a preliminary discussion based on available theoretical data indicates that the diameters of the particles are of the order of I5om~L. The present limitations of such an analysis are discussed