Ultraviolet spectroscopy of phi Per.

Abstract

Ultraviolet observations at high dispersion of Phi Persei obtained on the IUE satellite are described. The interstellar lines are separated from the stellar and shell lines, and all the lines are identified. The velocity of the interstellar medium in the direction of Phi Per is estimated to be about 34 km/sec. A model of the system based on the ultraviolet stellar and shell lines together with some visual and infrared spectra is developed. Although mass loss would not normally be expected for a star of this spectral class, it is shown that mass loss or interchange occurs at a rate of about 10 to the -9th solar masses/year. It is suggested that the mechanism for the mass loss is reduced escape velocity in the equatorial regions due to the high rotational velocity of the star, combined with escape from beyond the critical Roche surface of the system.