VOYAGER OBSERVATIONS OF THE COMPANION OF THE CLASSICAL CEPHEID S-MUSCAE

We have observed the companion of the Cepheid S Mus with the Voyager u ltraviolet spectrometer, including a spectrum of the background. We ha ve derived the energy distribution from 912 to 3200 Angstrom using the reddening obtained from Cepheid colors corrected for the effect of th e companion. This has been compared with three Morgan-Keenan ''dagger' ' spectral standards of appropriate spectral types. The addition of th e Voyager flux to the energy distribution provides a clear discriminan t 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 th e H-2 absorption correction, even the S Mus B spectrum uncorrected for H-2 absorption has more flux at 1000 Angstrom than the B5 star. (C) 1 996 American Astronomical Society.