Phase variations of 88 Herculis : do the UV observations confirm a connection between these variations and the changes of the phospheric parameters of the underlying star ?

Abstract

It is shown that the observed far-UV flux variation of 88 Herculis from 1976 to 1979 is lower than previously reported. The variation from 1979 to 1983 is difficult to confirm. The remaining flux changes cannot be attributed to changes in the stellar luminosity of the star. Furthermore, the constancies of the size and of the position-wavelength of the stellar Balmer discontinuity during the flux variations rule out any significant change of the photospheric parameters over the whole period of observation. The change in the observed luminosity from the B to the Be-shell phase can be understood as a consequence of changes in the shape of the envelope.