The first ultraviolet spectrum of the southwest (SW) component of the symmetrical jet in the R Aquarii binary system has been obtained in the range 1200-2000 A with the International Ultraviolet Explorer (IUE). These results are compared to more encompassing spectra (1200-3200 A) of the central H II region taken at the same time and also similar spectra of the northeast (NE) jet component obtained 6 months earlier. Moreover, optical spectra of both the NE and SW jet components in the range 3400-9800 A were obtained within ~ 6 months and ~ 1 month, respectively, of the ultraviolet spectra. These highly complementary observations argue that excitation of the symmetrical jet may be due to shock excitation as the jet components overtake and impact the previously ionized material associated with the expanding inner nebulosity. We discuss the problems with this shock model as well as problems with competing photoionization models. We suggest that the jet components were ejected less than 90 years ago.
Hollis, J.M., Oliversen, R.J., Kafatos, M., Michalitsianos, A.J., Wagner, R.M. (1991). Ultraviolet and Optical Spectroscopy of the R Aquarii Symmetrical Jet, Astrophysical Journal, 377:227-234. doi: 10.1086/170349