Ultraviolet spectra obtained in the 1200-3200 A range over the course of 4 yr with the International Ultraviolet Explorer (IUE) indicate that the extended nebular features which resemble a jet in the peculiar variable R Aquarii (M7e+pec) have increased in excitation in 1985. This is indicated by the appearance of He II Al640 and N v AA1238, 1240 in the jet features and is consistent with the detection of soft X-rays, as found with EXOSAT in 1985. We have analyzed the emission properties of the compact H II region that surrounds the unresolved binary, and those of the extended nebular jet, from the low-resolution IUE spectra which we obtained of these regions. In particular, the UV line intensities observed in the jet appear variable on a time scale of ~1.5 yr. A new accretion disk model is proposed that explains the kinematic and ionization properties of discrete components which comprise the jet emission nebulosity, the appearance of the jet in the 1980s, and morphology that uniquely characterizes the R Aquarii system at radio, optical, UV, and X-ray wavelengths.
Kafatos, M., Michalitsianos, A,G., Hollis, J,M. (1986) Ultraviolet Variability and Mass Expulsion from R Aquarii, The Astrophysical Journal Supplement Series, 62: 853-874. doi: 10.1086/191158