Observations of RR Lyrae and X Arietis with the IUE satellite.

Seven low dispersion spectra of RR Lyr and 11 of X Ari were obtained with the long wave redundant camera of IUE. The RR Lyr was also observed in the low-dispersion mode with the SWP camera and in the high-dispersion mode with the LWR camera. The observed fluxes were compared with fluxes calculated by using synthetic spectra and angular diameters determined from photometry at longer wavelengths. The observed fluxes for RR Lyr were found to be significantly fainter than the computed ones. The RR Lyr was also found to be 0.4 magnitudes fainter at 2200A and 2500A during minimum light than it was during previous ultraviolet observations with the ANS satellite. It is suggested that both these differences are due to the star's secondary cycle (the Blazhko effect). One of the high-dispersion exposures made near maximum light was deep enough to reveal the cores of the Mg II h and k lines. No emission was observed and a strong interstellar absorption component was present. Emission features were generally absent from the SWP spectra. An agreement between observed and calculated fluxes was found for X Ari for which no Blazhko effect is observed.