The envelope of Pleione in 1976.

In 1976 Pleione showed a further development of the shell characteristics. The spectrograms obtained in August and November 1976 were measured for the radial velocities, central intensities, and half half- widths of the shell lines of the Balmer series. The mean radial velocity was 8.7 km 1 in August and 3.0 km 1 in November. No Balmer progression was seen. The envelope continued its slow expansion in the equatorial plane as well as in the vertical direction. While the mean density in the envelope decreased due to expansion, the mass of the envelope increased up to 1.4 x . The mass-loss rate was 4 X . The overall picture of the envelope is a smooth progression of the preceding variation in 1972-1975. Key words: Be stars; Extended atmosphere; Pleione; Shell stars; Spectral variation.