EVOLUTION OF THE CIRCUMSTELLAR SHELL OF PLEIONE (1981-94)

Three spectra of Pleione (1981, 1987-88, 1994), obtained in the blue w avelength range, show strong long-term changes which indicate that the surrounding shell, first rather cool and close to the central star, t hen expands gradually in the equatorial plane of the star and towards the poles. From 1981 to 1987-88, the spectrum of Pleione is that of th e central star, with a cool shell which globally mimics a late-type st ar. The year 1994 is marked by a pure and stronger Be spectrum, with n o shell line.