IUE observations of the hot components in two symbiotic stars

Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, subluminous companion. In one case, the hot companion manifests itself by exciting a compact nebulosity; in the other case the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.