The Far UV Variability of τ Her (HD 147394) Recorded by IUE

Abstract

Abstract Evidence is presented that the far-ultraviolet flux of τ Her recorded by the International Ultraviolet Explorer is variable in a series of six spectra taken consecutively over 4 hr and 45 minutes The centroids of the resonance lines of O i, C ii and Si ii are blueshifted in several spectra and resume their original positions over a timescale of 3 hr 5 minutes. The FUV flux also varies over the same timescale. The far-ultraviolet variability is discussed in light of the recent TESS lightcurve observed for τ Her.