Voyager Observations of the Companiion of the Classical Cepheid S MUSCAE

Abstract

We have observed the companion of the Cepheid S Mus with the Voyager ultraviolet spectrometer, including a spectrum of the background. We have derived the energy distribution from 912 to 3200 Å using the reddening obtained from Cepheid colors corrected for the effect of the companion. This has been compared with three Morgan-Keenan "dagger" spectral standards of appropriate spectral types. The addition of the Voyager flux to the energy distribution provides a clear discriminant between B3 and B5, and shows that S Mus B is a good match to both of the B3 V spectral standards. Although there is some uncertainty in the H2 absorption correction, even the S Mus B spectrum uncorrected for H2 absorption has more flux at 1000 Å than the B5 star.