The ultraviolet spectrum of the eclipsing binary ZET Aur.

Abstract

The ultraviolet spectrum of the atmospheric binary Zeta Aur has been observed with the IUE, in the high resolution mode, at the 0.91 and 0.27 spectrum phases. The phases were computed from the epoch minimum light, using the epoch and period given by Kukarkin et al. (1969), and from the periastron passage, using the epoch given by Wright (1970). The radial velocities of the B star were derived using Wright's data for the radial velocity curve of the K primary and the values of K1 and K2. Results obtained by comparing the spectra of the two phases are presented, and include the following: (1) the larger variations are shown by the resonance lines C IV, N V, and Si IV, which are strongly enhanced at the 0.27 phase; (2) radial velocity variations of the various components are shown by the resonance lines Al III and F III, multiplet 34; and (3) the near ultraviolet spectrum has been observed only at the 0.91 phase, and it is dominated by lines of once-ionized metals.